Detection of Paralytic Shellfish Toxins in Southern Rock Lobster Jasus edwardsii Using the Qualitative Neogen™ Lateral Flow Immunoassay: Single-Laboratory Validation

Signal-on electrogenerated chemiluminescence detection of gonyautoxin 1/4 based on proximity ligation-induced an electrode-bound pseudoknot DNA

A "signal on" electrogenerated chemiluminescence (electrochemiluminescence, ECL) aptasensor based on proximity ligation-induced an electrode-bound pseudoknot DNA for sensitive detection of gonyautoxin 1/4 (GTX1/4) was developed on basis of the competitive type reaction mode. Aptamer was adopted as recognition element. Ru(bpy)32+ as ECL signal, was attached on the glassy carbon electrode (GCE) surface modified with nafion and gold nanoparticles (AuNPs) by electrostatic attraction to obtain the ECL platform. The pseudoknot DNA as capture probe, was immobilized onto the ECL platform via Au-S bond to obtain the ECL aptasensor. In the absence of GTX1/4, Y-shape proximate cooperative complex among aptamer, pseudoknot DNA and DNA1 was formed, drawing the ferrocene groups Fc, as ECL quencher) of both pseudoknot DNA and DNA1 near the electrode surface and resulting in low ECL signal. In the presence of GTX1/4, GTX1/4 competed with pseudoknot DNA and DNA1 for aptamer in homogeneous solution, preventing the formation of proximate cooperative complex and keeping the capture DNA in the pseudoknot conformation with Fc groups far away from the electrode surface, generating a high ECL signal. The recovery of ECL intensity increased with the GTX1/4 concentration and allowed the detection of GTX1/4 in the range of 0.01 ng/mL to 10 ng/mL with a detection of limit as low as 6.56 pg/mL. Additionally, the accuracy of this method was validated for analysis of spiked sea water samples with good recoveries, which indicates great potential in commercial application.

Field Validation of the Southern Rock Lobster Paralytic Shellfish Toxin Monitoring Program in Tasmania, Australia

Paralytic shellfish toxins (PST) are found in the hepatopancreas of Southern Rock Lobster Jasus edwardsii from the east coast of Tasmania in association with blooms of the toxic dinoflagellate Alexandrium catenella. Tasmania’s rock lobster fishery is one of the state’s most important wild capture fisheries, supporting a significant commercial industry (AUD 97M) and recreational fishing sector. A comprehensive 8 years of field data collected across multiple sites has allowed continued improvements to the risk management program protecting public health and market access for the Tasmanian lobster fishery. High variability was seen in toxin levels between individuals, sites, months, and years. The highest risk sites were those on the central east coast, with July to January identified as the most at-risk months. Relatively high uptake rates were observed (exponential rate of 2% per day), similar to filter-feeding mussels, and meant that lobster accumulated toxins quickly. Similarly, lobsters were relatively fast detoxifiers, losing up to 3% PST per day, following bloom demise. Mussel sentinel lines were effective in indicating a risk of elevated PST in lobster hepatopancreas, with annual baseline monitoring costing approximately 0.06% of the industry value. In addition, it was determined that if the mean hepatopancreas PST levels in five individual lobsters from a site were <0.22 mg STX equiv. kg⁻¹, there is a 97.5% probability that any lobster from that site would be below the bivalve maximum level of 0.8 mg STX equiv. kg⁻¹. The combination of using a sentinel species to identify risk areas and sampling five individual lobsters at a particular site, provides a cost-effective strategy for managing PST risk in the Tasmanian commercial lobster fishery.