Changing Trends in Paralytic Shellfish Poisonings Reflect Increasing Sea Surface Temperatures and Practices of Indigenous and Recreational Harvesters in British Columbia, Canada.

Paralytic shellfish poisoning (PSP) occurs when shellfish contaminated with saxitoxin or equivalent paralytic shellfish toxins (PSTs) are ingested. In British Columbia, Canada, documented poisonings are increasing in frequency based on 62 investigations identified from 1941-2020. Two PSP investigations were reported between 1941 and 1960 compared to 31 since 2001 (p < 0.0001) coincident with rising global temperatures (r2 = 0.76, p < 0.006). The majority of PSP investigations (71%) and cases (69%) were linked to self-harvested shellfish. Far more investigations involved harvests by indigenous communities (24%) than by commercial and recreational groups. Single-case-exposure investigations increased by more than 3.5 times in the decade 2011-2020 compared to previous periods. Clams (47%); mussels (26%); oysters (14%); scallops (6%); and, in more recent years, crabs (4%) were linked to illnesses. To guide understanding of self-harvesting consumption risks, we recommend collecting data to determine when PST-producing algae are present in high concentrations, improving the quality of data in online shellfish harvest maps to include dates of last testing; biotoxin testing results; and a description of bivalve species tested. Over reliance on toxin results in biomonitored species may not address actual consumption risks for unmonitored species harvested from the same area. We further recommend introducing phytoplankton monitoring in remote indigenous communities where self-harvesting is common and toxin testing is unavailable, as well as continuing participatory education about biotoxin risks in seafoods.

Drastic hypothermia after intraperitoneal injection of okadaic acid, a diarrhetic shellfish poisoning toxin, in mice.

The mouse bioassay for diarrhetic shellfish poisoning (DSP) toxins had been used as the official method in Japan and also used in the world. In this study, hypothermia, one of the symptoms observed in mice after inoculation with DSP toxins, were characterized. Lethal and sublethal doses of okadaic acid (OA), a representative component of DSP toxins, were inoculated intraperitoneally into mice. Body-temperature changes over time were measured by an electronic thermometer or monitored by an infrared camera. Drastic hypothermia (<30°C in some mice) was observed in a few hours after administration of a lethal dose of OA. Dose-dependency was clearly seen between doses of OA inoculated and body-temperature decrease. Drastic hypothermia was also detected by using an infrared camera. These results suggest that hypothermia could be used as an index for the humane endpoint in experimental animal toxicological studies.

Genetics of Marine Organisms Associated with Human Health.

Marine habitats harbour a large variety of organisms that belong to diverse taxa; from bacteria and unicellular eukaryotes to fungi, animals, and plants. Although we have only started to understand the diversity and structure of marine communities, it is clear that numerous marine species have or might have an impact on human health. Some are a source of natural products with potential or actual medical applications, others are toxic and harmful to humans, and some are used in biomedical research to help understand the molecular basis of human diseases. New molecular genetics and genomic methods provide powerful and ever more indispensable tools for studying marine organisms and all aspects of their influence on human health. Herein, we present work using the latest research, which mostly uses genomics, to tackle the questions related with the topic of the issue.

Limnological Differences in a Two-Basin Lake Help to Explain the Occurrence of Anatoxin-a, Paralytic Shellfish Poisoning Toxins, and Microcystins.

Chautauqua Lake, New York, is a two-basin lake with a deeper, cooler, and less nutrient-rich Northern Basin, and a warmer, shallower, nutrient-replete Southern Basin. The lake is populated by a complex mixture of cyanobacteria, with toxigenic strains that produce microcystins, anatoxins, and paralytic shellfish poisoning toxins (PSTs). Samples collected from 24 sites were analyzed for these three toxin classes over four years spanning 2014-2017. Concentrations of the three toxin groups varied widely both within and between years. During the study, the mean and median concentrations of microcystins, anatoxin-a, and PSTs were 91 and 4.0 µg/L, 0.62 and 0.33 µg/L, and 32 and 16 µg/L, respectively. Dihydro-anatoxin was only detected once in Chautauqua Lake, while homo-anatoxin was never detected. The Northern Basin had larger basin-wide higher biomass blooms with higher concentrations of toxins relative to the more eutrophied Southern Basin, however blooms in the North Basin were infrequent. Chlorophyll concentrations and toxins in the two basins were correlated with different sets of environmental and physical parameters, suggesting that implementing controls to reduce toxin loads may require applications focused on more than reductions in cyanobacterial bloom density (e.g., reduction of phosphorus inputs), and that lake limnological factors and morphology are important determinants in the selection of an appropriate management strategy. Chautauqua Lake is a drinking water source and is also heavily used for recreation. Drinking water from Chautauqua Lake is unlikely to be a significant source of exposure to cyanotoxins due to the location of the intakes in the deeper North Basin, where there were generally low concentrations of toxins in open water; however, toxin levels in many blooms exceeded the US Environmental Protection Agency's recreational guidelines for exposure to cyanotoxins. Current cyanotoxin monitoring in Chautauqua Lake is focused on microcystins. However, the occurrence of blooms containing neurotoxic cyanotoxins in the absence of the microcystins indicates this restricted monitoring may not be sufficient when aiming to protect against exposure to cyanotoxins. The lake has a large number of tourist visitors; thus, special care should be taken to prevent recreational exposure within this group.

Effects of the DSP-toxic dinoflagellate Dinophysis acuta on clearance and respiration rate of the blue mussel, Mytilus edulis.

Diarrheic Shellfish Poisoning toxins (DST) are a severe health risk to shellfish consumers and can be a major problem for the shellfish industry. Bivalve molluscs can accumulate DST via ingestion of toxic dinoflagellates like Dinophysis spp., which are the most prominent producers of DST. The effects of DST-containing dinoflagellate Dinophysis acuta on bivalve clearance and respiration rate were investigated in the blue mussel (Mytilus edulis) exposed to different algal densities in a controlled laboratory study. Results showed that M. edulis exposed to D. acuta displayed a reduced clearance rate compared to M. edulis exposed to equivalent bio-volumes of the non-toxic cryptophyte Rhodomonas salina. Furthermore, M. edulis ceased to feed on D. acuta after 1 to 4 h, depending on D. acuta densities. The quickest response was observed at the highest densities of D. acuta. The estimated total amount of DST accumulated in the M. edulis exceeded the regulatory limit for human consumption and furthermore, intoxication of the M. edulis seemed to occur faster at high cell toxicity rather than at high cell density. However, respiration rates were, similar, irrespective of whether M. edulis were fed single diets of R. salina, D. acuta or a mixed diet of both algal species. In conclusion, the DST-containing D. acuta had a severe negative effect on the clearance of M. edulis, which can affect the conditions of the M. edulis negatively. Hence, DST may cause low quality M. edulis, due to reduced feeding when exposed to DST-containing D. acuta.

Clinical signs and mortality of non-released stranded California sea lions housed in display facilities: the suspected role of prior exposure to algal toxins.

Stranded California sea lions considered unable to survive in the wild are often placed in public display facilities. Exposure to the biotoxin domoic acid (DA) is a common cause of stranding, and chronic effects are observed long after initial exposure. Medical records for 171 sea lions placed in US institutions between 2000 and 2016 were reviewed, including results from clinical examinations, histopathology, behavioural testing and advanced imaging. There was a statistically significant increase in neurological disease detected in neonates (24%) compared with other age classes (11%). Sixty per cent of all neurological cases died during the study period. In the 11 neurological neonate cases, six died (55%) and five are still alive with three of five developing epilepsy during placement. Of the six neurological neonate cases that died, one was attributed to DA toxicosis, one to seizures and four to acute unexplained neurological disease. This survey suggests delayed neurological disease can develop in sea lions after stranding as neonates. These data coupled with stranding records and epidemiological data on DA-producing algal blooms suggest further research into effects of neonatal exposure to DA on risk of neurological disease in later life is warranted. California sea lions offer a natural model of DA exposure to study such effects.

HABscope: A tool for use by citizen scientists to facilitate early warning of respiratory irritation caused by toxic blooms of Karenia brevis.

Blooms of the toxic microalga Karenia brevis occur seasonally in Florida, Texas and other portions of the Gulf of Mexico. Brevetoxins produced during Karenia blooms can cause neurotoxic shellfish poisoning in humans, massive fish kills, and the death of marine mammals and birds. Brevetoxin-containing aerosols are an additional problem, having a severe impact on beachgoers, triggering coughing, eye and throat irritation in healthy individuals, and more serious respiratory distress in those with asthma or other breathing disorders. The blooms and associated aerosol impacts are patchy in nature, often affecting one beach but having no impact on an adjacent beach. To provide timely information to visitors about which beaches are low-risk, we developed HABscope; a low cost (~$400) microscope system that can be used in the field by citizen scientists with cell phones to enumerate K. brevis cell concentrations in the water along each beach. The HABscope system operates by capturing short videos of collected water samples and uploading them to a central server for rapid enumeration of K. brevis cells using calibrated recognition software. The HABscope has a detection threshold of about 100,000 cells, which is the point when respiratory risk becomes evident. Higher concentrations are reliably estimated up to 10 million cells L-1. When deployed by volunteer citizen scientists, the HABscope consistently distinguished low, medium, and high concentrations of cells in the water. The volunteers were able to collect data on most days during a severe bloom. This indicates that the HABscope can provide an effective capability to significantly increase the sampling coverage during Karenia brevis blooms.

Detection to treatment and global impacts of algal toxins.

Harmful algal blooms in the past three decades appear to have grown in incidence, intensity and geographical distribution with negative impacts on public health and economy values. Each year the algal biotoxins are responsible for more than 60.000 intoxications with an associated mortality rate of 1.5%. The present review summarizes current knowledge and perspectives on marine and freshwater algal toxins with an emphasis on different genus of algae capable to produce toxins and their physiology. The typologies of toxins, their chemical structure and mechanisms of action, the factors that stimulate their biosynthesis and the current techniques used for algal toxins removal will be also reviewed.

Up-regulation of Nrf2-dependent antioxidant defenses in Perna viridis after exposed to Prorocentrum lima.

It is well documented that diarrhetic shellfish poisoning (DSP) toxins have strong genetic toxicity, cytotoxicity and oxidative damage to bivalve species. However, these toxic effects seem to decrease with the extension of exposure time and the increment of the toxin concentration, the mechanism involved remained unclear, though. In this paper, we found that expression of the genes related to cytoskeleton and Nrf2 signaling pathway displayed different changes over time in the gill of Perna viridis after exposure to DSP toxins-producing microalga Prorocentrum lima. During the short-term exposure (3 h and 6 h), KEAP1 gene expression was significantly up-regulated, coupled with up-regulation of MRP, ABCB1 and CAT transcriptions and down-regulation of GPx1 and NQO1 mRNA. After longer exposure to high density of P. lima, Nrf2 was significantly up-regulated, accompanied with up-regulation of Nrf2 pathway related genes such as NQO1, SOD, GST-ω and ABCB1, whereas KEAP1 was down-regulated. TUBA1C and TUBB1 transcripts were significantly down-regulated after short-term exposure of P. lima, but both of them were up-regulated at 96 h after exposure to high density of P. lima. Paraffin section demonstrated that P. lima had a strong damage on the gill of mussels during the short-term exposure. However, the negative effect to the gill decreased, and the gill restored after longer exposure (96 h). Taking together, we proposed that P. lima had a negative impact on cytoskeleton of mussel gill tissue, could cause oxidative damage to the gills. However, longer exposure of P. lima in high density could activate Nrf2 signaling pathway, thereby reducing the influence of toxin on mussel. Our study might provide a novel clue for the resistance mechanism of shellfish to DSP toxins.

piRNA-DQ722010 contributes to prostate hyperplasia of the male offspring mice after the maternal exposed to microcystin-leucine arginine.

BACKGROUND: Microcystin-leucine arginine (MC-LR) could disrupt prostate development and cause prostate hyperplasia. But whether and how maternal and before-weaning MC-LR exposure causes prostate hyperplasia in male offspring by changing expression profile of P-element-induced wimpy (PIWI)-interacting RNAs (piRNAs) have not yet been reported. METHODS: From the 12th day in the embryonic period to the 21st day after offspring birth, three groups of pregnant mice that were randomly assigned were exposed to 0, 10, and 50 µg/L of MC-LR through drinking water followed by the analyses of their male offspring. Abortion rate and litter size of maternal mice were recorded. The prostate histopathology was observed. Differential expressed piRNAs of prostate were screened by piRNA microarray analysis. Murine prostate cancer cell line (RM-1) was used for further mechanism study. Luciferase report assay was used to determine the relationship between piRNA-DQ722010 and polypeptide 3 (Pik3r3). RESULTS: The downregulated expression of piRNA-DQ722010 was the most significant in piRNA microarray analysis in 10 µg/L MC-LR treated group, while Pik3r3 was significantly upregulated, consistent with the results that a distinct prostatic epithelial hyperplasia was observed and phosphoinositide-3-kinase (PI3K)/protien kinase B (AKT) signaling pathway was activated. Pik3r3 was verified as the target gene of piRNA-DQ722010. In addition, we found MC-LR decreased the expression of PIWI-like RNA-mediated gene silencing 2 (Piwil2) and 4 (Piwil4) both in vivo and in vitro, and both Piwil4 and Piwil2 could regulate the expression of DQ722010. CONCLUSION: MC-LR caused downregulation of piRNA-DQ722010 and PIWI proteins, while piRNA-DQ722010 downregulation promoted activation of PI3K/AKT signaling pathway inducing prostate hyperplasia by upregulating the expression of Pik3r3. In contrast, piRNA-DQ722010 downregulation may be attributed to PIWI proteins downregulation.

Ocean acidification exacerbates the effects of paralytic shellfish toxins on the fitness of the edible mussel Mytilus chilensis.

High latitudes are considered particularly vulnerable to ocean acidification, since they are naturally low in carbonate ions. The edible mussel Mytilus chilensis is a common calcifier inhabiting marine ecosystems of the southern Chile, where culturing of this species is concentrated and where algal blooms produced by the toxic dinoflagellate A. catenella are becoming more frequent. Juvenile Mytilus chilensis were exposed to experimental conditions simulating two environmental phenomena: pCO2 increase and the presence of paralytic shellfish toxins (PST) produced by the dinoflagellate Alexandrium catenella. Individuals were exposed to two levels of pCO2: 380 µatm (control condition) and 1000 µatm (future conditions) over a period of 39 days (acclimation), followed by another period of 40 days exposure to a combination of pCO2 and PST. Both factors significantly affected most of the physiological variables measured (feeding, metabolism and scope for growth). However, these effects greatly varied over time, which can be explained by the high individual variability described for mussels exposed to different environmental conditions. Absorption efficiency was not affected by the independent effect of the toxic diet; however, the diet and pCO2 interaction affected it significantly. The inhibition of the physiological processes related with energy acquisition by diets containing PST, may negatively impact mussel fitness, which could have important consequences for both wild and cultured mussel populations, and thus, for socioeconomic development in southern Chile.

Acute kidney injury with consumption of raw gall bladder of Indian carp fish (Labeo rohita): A single center study from India.

AIM: This retrospective study examined the clinical presentation and outcome of all patients who presented with acute kidney injury (AKI) following consumption of uncooked fish gallbladder as folk medicine. METHODS: We reviewed all cases admitted at our institute between 1 January 1997 and 31 December 2016 following ingestion of fish gallbladder (Indian carp/Labeo rohita). RESULTS: A total 32 of patients were included, with a male: female ratio of 3:1 and mean age 44.34 ± 13.33 years. The mean number of gall bladder consumed was 4.59 ± 4.75. All 32 patients presented with hepatic and renal failure. The mean duration of onset of symptoms following ingestion was 6.47 ± 2.84 h. At the time of admission, urine output was 187.9 ± 141 mL/24 h, serum creatinine 11.66 ± 2.50 mg/dL, serum bilirubin 6.14 ± 3.91 mg/dL, serum glutamate-pyruvate transaminase (SGPT) 687 ± 458 IU/L and serum glutamic oxaloacetic transaminase (SGOT) 188 ± 181 IU/L. All but one patient required haemodialysis. Twenty-seven patients were discharged with recovering acute kidney injury while five patients died. Mean duration of hospital stay was 12.94 ± 8.31 days. Mean number of haemodialysis sessions received by patients was 4.59 ± 3.12. Interval between consumption and onset of symptoms, serum bilirubin and SGPT were found to be significantly different between those who survived and died. CONCLUSION: Acute kidney injury associated with ingestion of raw fish gallbladder is associated with significant morbidity and mortality.

A diagnostic red herring.

CLINICAL INTRODUCTION: A 29-year-old keen parachutist presented to the emergency services in Cyprus complaining of sudden-onset facial flushing, dizziness and a widespread rash. The episode began on a hot day, 1 hour after she had eaten a breakfast of tinned tuna, and while she was ascending in an aircraft to parachute from 10 000 ft. She completed her jump uneventfully. She had no significant medical history (figure 1).emermed;35/3/184/F1F1F1Figure 1Patient's legs on presentation; this rash was generalised. QUESTION: Based on the history and rash, which ONE of the following is the most likely diagnosis?Fish allergyHeat-related eruptionScombrotoxin poisoningStress-induced urticaria.

Cyanobacterial Toxins of the Laurentian Great Lakes, Their Toxicological Effects, and Numerical Limits in Drinking Water.

Cyanobacteria are ubiquitous phototrophic bacteria that inhabit diverse environments across the planet. Seasonally, they dominate many eutrophic lakes impacted by excess nitrogen (N) and phosphorus (P) forming dense accumulations of biomass known as cyanobacterial harmful algal blooms or cyanoHABs. Their dominance in eutrophic lakes is attributed to a variety of unique adaptations including N and P concentrating mechanisms, N2 fixation, colony formation that inhibits predation, vertical movement via gas vesicles, and the production of toxic or otherwise bioactive molecules. While some of these molecules have been explored for their medicinal benefits, others are potent toxins harmful to humans, animals, and other wildlife known as cyanotoxins. In humans these cyanotoxins affect various tissues, including the liver, central and peripheral nervous system, kidneys, and reproductive organs among others. They induce acute effects at low doses in the parts-per-billion range and some are tumor promoters linked to chronic diseases such as liver and colorectal cancer. The occurrence of cyanoHABs and cyanotoxins in lakes presents challenges for maintaining safe recreational aquatic environments and the production of potable drinking water. CyanoHABs are a growing problem in the North American (Laurentian) Great Lakes basin. This review summarizes information on the occurrence of cyanoHABs in the Great Lakes, toxicological effects of cyanotoxins, and appropriate numerical limits on cyanotoxins in finished drinking water.

Yessotoxin, a Marine Toxin, Exhibits Anti-Allergic and Anti-Tumoural Activities Inhibiting Melanoma Tumour Growth in a Preclinical Model.

Yessotoxins (YTXs) are a group of marine toxins produced by the dinoflagellates Protoceratium reticulatum, Lingulodinium polyedrum and Gonyaulax spinifera. They may have medical interest due to their potential role as anti-allergic but also anti-cancer compounds. However, their biological activities remain poorly characterized. Here, we show that the small molecular compound YTX causes a slight but significant reduction of the ability of mast cells to degranulate. Strikingly, further examination revealed that YTX had a marked and selective cytotoxicity for the RBL-2H3 mast cell line inducing apoptosis, while primary bone marrow derived mast cells were highly resistant. In addition, YTX exhibited strong cytotoxicity against the human B-chronic lymphocytic leukaemia cell line MEC1 and the murine melanoma cell line B16F10. To analyse the potential role of YTX as an anti-cancer drug in vivo we used the well-established B16F10 melanoma preclinical mouse model. Our results demonstrate that a few local application of YTX around established tumours dramatically diminished tumour growth in the absence of any significant toxicity as determined by the absence of weight loss and haematological alterations. Our data support that YTX may have a minor role as an anti-allergic drug, but reveals an important potential for its use as an anti-cancer drug.

The association between razor clam consumption and memory in the CoASTAL Cohort.

This study represents a preliminary effort to examine the possible impacts of chronic, low level Domoic Acid (DA) exposure on memory in the CoASTAL cohort. Five hundred thirteen men and women representing three Native American Tribes were studied with standard measures of cognition and razor clam consumption (a known vector of DA exposure) over a four year period. In addition, a pilot metric of DA concentration exposure was used which took into consideration average DA concentration levels in source beaches as well as consumption. Based upon GEE analysis, controlling for age, sex, race, year, education level, tribe, and employment status, findings indicated that high razor clam consumers (15 or more per month) had isolated decrements on some measures of memory (p=.02 to .03), with other cognitive functions unaffected. The relatively lower memory scores were still within normal limits, thus not clinically significant. The pilot DA exposure metric had no association with any aspect of cognition or behavior. There is a possible association between long term, low level exposure to DA through heavy razor clam consumption and memory. The availability of a reliable biological marker for human exposure to DA is needed.

Scombroid syndrome: it seems to be fish allergy but... it isn't.

PURPOSE OF REVIEW: Scombroid poisoning is a frequent cause of admission in emergency department. In everyday clinical practice, it can be difficult to discriminate between scombroid syndrome and fish allergy. The aim of this review is to provide the clinician some instruments to make a correct differential diagnosis. RECENT FINDINGS: In the last few years, a better characterization of scombroid syndrome occurred, in particular regarding its possible severe presentations. Two cases of Kounis syndrome secondary to scombroid syndrome have been described and in these cases a differential diagnosis in patients with this clinical presentation can be even more difficult. Finally, in term of diagnosis, the useful role of serum tryptase was recently consolidated. SUMMARY: Scombroid syndrome is a histamine-induced reaction because of the ingestion of histamine-contaminated fish, whereas fish allergy is an IgE-mediated reaction. Clinical presentation can be similar and for this reason scombroid syndrome is often misdiagnosed. The differences lie in pathogenic mechanisms, possible outcome, therapy, and prevention measures. Moreover, some laboratory tests are helpful to discriminate between the two diseases.

How Safe Is Safe for Marine Toxins Monitoring?

Current regulation for marine toxins requires a monitoring method based on mass spectrometric analysis. This method is pre-targeted, hence after searching for pre-assigned masses, it identifies those compounds that were pre-defined with available calibrants. Therefore, the scope for detecting novel toxins which are not included in the monitoring protocol are very limited. In addition to this, there is a poor comprehension of the toxicity of some marine toxin groups. Also, the validity of the current approach is questioned by the lack of sufficient calibrants, and by the insufficient coverage by current legislation of the toxins reported to be present in shellfish. As an example, tetrodotoxin, palytoxin analogs, or cyclic imines are mentioned as indicators of gaps in the system that require a solid comprehension to assure consumers are protected.

The anti-tumour activity of rLj-RGD4, an RGD toxin protein from Lampetra japonica, on human laryngeal squamous carcinoma Hep-2 cells in nude mice.

PURPOSE: The objective of this study is to investigate the antiproliferative activity and mechanism of integrin-binding rLj-RGD4 in a Hep-2 human laryngeal carcinoma-bearing nude mouse model. METHODS: Human laryngeal squamous carcinoma cells (Hep-2) were inoculated subcutaneously into the axilla of nude mice to generate a Hep-2 human laryngeal carcinoma-bearing nude mouse model. When the Hep-2 xenograft model was successfully established, the animals were randomly separated into five groups. Three groups were treated with different dosages of rLj-RGD4. Cisplatin was administered to the positive control group, and normal saline (NaCl) was administered to the negative control group for 3 weeks. The body weights and the survival of the nude mice were evaluated, and the volumes and weights of the solid tumours were measured. The mechanism underlying rLj-RGD4 inhibition of tumour growth in transplanted Hep-2 human laryngeal carcinoma-bearing nude mice was evaluated by haematoxylin-eosin (HE) staining, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling (TUNEL), measurement of intratumoural microvessel density (MVD), Western blotting, and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). RESULTS: The tumour volumes and weights of the treatment groups were reduced compared with the model group, and survival times were improved by rLj-RGD4 treatment in Hep-2 human laryngeal carcinoma-bearing nude mice. The number of apoptotic Hep-2 human cells and intratumoural MVD significantly decreased after the administration of rLj-RGD4. In the xenograft tissue of animals treated with rLj-RGD4, FAK, PI3K, and Akt expression was unaltered, whereas P-FAK, P-PI3K, Bcl-2, P-Akt, and VEGF levels were down-regulated. In addition, activated caspase-3, activated caspase-9, and Bax levels were up-regulated. CONCLUSION: rLj-RGD4 exhibits potent in vivo activity and inhibits the growth of transplanted Hep-2 human laryngeal carcinoma cells in a nude mouse model. Thus, these results indicate that the recombinant RGD toxin protein rLj-RGD4 may serve as a potent clinical therapy for human laryngeal squamous carcinoma.