This is among the hardly any works reported in the literature of such cross types assays for small-molecule analytes whose compatibility with field samples is also demonstrated. Introduction Tetrodotoxin (TTX) is an extremely potent neurotoxin made by marine bacteria, which is connected with severe sea food poisoning after intake of pufferfish (Tetraodontidae family members).1 Its paralytic toxic results are based on its selective binding to voltage-gated sodium stations and interfering using the neural transmission.2 Symptoms of TTX intoxication include numbness feeling in the mouth area, headache, vomiting, and muscle weakness,3 and fatal respiratory or heart failure have also been reported.4 This low-molecular-weight toxin (319.3 g/mol) was originally isolated from pufferfish in 19095,6 and was later also found in other marine7 and terrestrial8 species. The assay was successfully applied to the quantification of TTX in pufferfish extracts, and the results obtained correlated very well with a competitive magnetic bead-based immunoassay performed in parallel for comparison. This is one of the very few works reported in the literature of such hybrid assays for small-molecule analytes whose compatibility with field samples is also exhibited. Introduction Tetrodotoxin (TTX) is usually a very potent neurotoxin produced by marine bacteria, and it is associated with severe seafood poisoning after consumption of pufferfish (Tetraodontidae family).1 Its paralytic toxic effects derive from its selective binding to voltage-gated sodium channels and ultimately interfering with the neural transmission.2 Symptoms of TTX intoxication include numbness sensation in the mouth, headache, vomiting, and muscle weakness,3 and fatal respiratory or heart failure have also been reported.4 This low-molecular-weight toxin (319.3 g/mol) was originally isolated from pufferfish in 19095,6 and was later also found in other marine7 and terrestrial8 species. Even though it was initially believed that TTX was produced by the pufferfish itself, marine bacterial species have been postulated to be able to produce TTX,9 suggesting that symbiotic marine bacteria could be the primary source of TTX that bioaccumulates in pufferfish and other marine species and finally reaches humans through the food chain. As recently reported, there are more than 30 different bacteria genera capable of producing TTX that have been isolated, among which the most common is Retaspimycin the sp.10 To date, however, there is still some discussion regarding the TTX production/biosynthesis as well as the pathway of TTX bioaccumulation in marine ecosystems.11 Pufferfish poisoning is common of warm waters and was regarded as a problem confined to Asian countries,1,12 including Thailand,5 Taiwan,13 Singapore,14 Cambodia,15 Bangladesh,16 and India.17,18 However, Retaspimycin toxic pufferfish species have expanded to other regions, and there have been an increasing number of reports of incidences in the Mediterranean Sea, which has been attributed to the opening of the Suez Canal (the Lessepsian migration), which resulted in the migration of species from the Red Sea to colonize the Mediterranean Sea,19?22 the Aegean Sea,23 the Adriatic Sea,24 and Oman,25 and there have also been reports of the incidence of tetrodotoxin in Australia26 and the United States,27 highlighting the widespread distribution of the toxin. Additionally, TTX has been recently found in shellfish, particularly in European countries such as the United Kingdom,28 Portugal,29,30 Greece,31 the Netherlands,32 Spain,33 Italy,34 and France,35 although usually at very low concentrations. Nevertheless, it is now considered that TTX may pose a food safety risk even in nonendemic areas. TTX is highly toxic. Pufferfish poisonings have revealed that ingestion of 0.18C0.2 mg of TTX might be near the minimum dose for developing TTX symptoms, and 2 mg is a lethal dose. However, the levels of TTX that result in acute toxicity or death in humans are still unclear, with some reports of human cases suggesting that acute poisoning can occur from doses of 4C42 mg/kg body weight or higher.36 In Japan, where pufferfish is considered a delicacy and highly consumed despite its potential toxicity, a limit of 2 mg of TTX equiv/kg has been used as a criterion to judge the acceptability Mouse monoclonal antibody to HAUSP / USP7. Ubiquitinating enzymes (UBEs) catalyze protein ubiquitination, a reversible process counteredby deubiquitinating enzyme (DUB) action. Five DUB subfamilies are recognized, including theUSP, UCH, OTU, MJD and JAMM enzymes. Herpesvirus-associated ubiquitin-specific protease(HAUSP, USP7) is an important deubiquitinase belonging to USP subfamily. A key HAUSPfunction is to bind and deubiquitinate the p53 transcription factor and an associated regulatorprotein Mdm2, thereby stabilizing both proteins. In addition to regulating essential components ofthe p53 pathway, HAUSP also modifies other ubiquitinylated proteins such as members of theFoxO family of forkhead transcription factors and the mitotic stress checkpoint protein CHFR of pufferfish as food,37 and a guide with the edible parts and species of pufferfish that are allowed for consumption has been published.38 In the USA, strong restrictions exist for the importation of pufferfish.39 In Europe, Retaspimycin fish of the family Tetraodontidae and Retaspimycin products derived from them must not be placed on the markets.40,41 Regarding shellfish, no regulations exist. Nevertheless, the European Food Safety Authority (EFSA) has recently published that concentrations below 44 g of TTX equiv/kg shellfish.