Establishment of human cerebral organoid systems to model early neural development and assess the central neurotoxicity of environmental toxins

Human brain development is a complex process,and animal models often have significant limitations.To address this,researchers have developed pluripotent stem cell-derived three-dimensional structures,known as brain-like organoids,to more accurately model early human brain development and disease.To enable more consistent and intuitive reproduction of early brain development,in this study,we incorporated forebrain organoid culture technology into the traditional unguided method of brain organoid culture.This involved embedding organoids in matrigel for only 7 days during the rapid expansion phase of the neural epithelium and then removing them from the matrigel for further cultivation,resulting in a new type of human brain organoid system.This cerebral organoid system replicated the temporospatial characteristics of early human brain development,including neuroepithelium derivation,neural progenitor cell production and maintenance,neuron differentiation and migration,and cortical layer patterning and formation,providing more consistent and reproducible organoids for developmental modeling and toxicology testing.As a proof of concept,we applied the heavy metal cadmium to this newly improved organoid system to test whether it could be used to evaluate the neurotoxicity of environmental toxins.Brain organoids exposed to cadmium for 7 or 14 days manifested severe damage and abnormalities in their neurodevelopmental patterns,including bursts of cortical cell death and premature differentiation.Cadmium exposure caused progressive depletion of neural progenitor cells and loss of organoid integrity,accompanied by compensatory cell proliferation at ectopic locations.The convenience,flexibility,and controllability of this newly developed organoid platform make it a powerful and affordable alternative to animal models for use in neurodevelopmental,neurological,and neurotoxicological studies.

Identification of Monitoring Organ in Bivalves for Early Warning of Paralytic Shellfish Toxins Accumulation

Bivalve farming plays a dominant role in mariculture in China.Paralytic shellfish toxins(PSTs)can be accumulated in bivalves and cause poisoning the consumers.A sensitive detection of PSTs can provide early warning to decrease poisoning events in bivalve consuming.PSTs are traditionally examined using the whole soft-tissues.However,PSTs accumulation varies dramatically in different tissues of bivalves.Some tough tissues/organs(such as mantle),which account for a large proportion of the total soft body,exhibit a lower accumulation of PSTs and make the toxin extraction time-and reagent-consuming,potentially decreasing the accuracy and sensitivity of PSTs monitoring in bivalves.To develop a sensitive and cost-effective approach for PSTs examination in massively farmed bivalves,we fed three commercially important bivalves,Yesso scallop Patinopecten yessoensis,Pacific oyster Crassostrea gigas,and blue mussel Mytilus edulis with PSTs-producing dinoflagellate Alexandrium catenella,and detected PSTs concentration in different tissues.For all three bivalve species,the digestive gland accumulated much more PSTs than other tissues,and the digestive gland’s toxicity was significantly correlated with the PSTs toxicity of the whole soft-tissues,with r^(2)=0.94,0.92,and 0.94 for Yesso scallop,Pacific oyster,and blue mussel,respectively.When the toxicity of the whole soft-tissues reached 80μgSTXeq(100g)^(−1),the regulatory limit for commercial shellfish,the digestive gland’s toxicity reached 571.48,498.90,and 859.20μgSTXeq(100g)^(−1) in Yesso scallop,Pacific oyster,and blue mussel,respectively.Our results indicate that digestive gland can be used for the sensitive and cost-effective monitoring of PSTs in bivalves.

Effect of Purified Paper Wasp Ropalidia marginata Venom Toxins on Different Biomolecules in Mice Serum

This study evaluated the effects of purified paper wasp Ropalidia marginata venoms on various biomolecules in the blood serum of albino mice. Changes in the concentration of some important macromolecules, i.e., proteins, free amino acids, uric acid, cholesterol, pyruvic acid, total lipids and glucose were noted down. These alterations were measured after intraperitoneal injection of 40% and 80% 24-hour LD50 purified Ropalidia marginata venom toxin. Serum total protein levels were found to decrease to 78% after 6 hrs, while serum free amino acid levels were significantly increased to 117% 6 hrs after venom injection compared to control. It was also found that serum uric acid levels increased to 138% after 8 hrs of venom injection compared to control. The increase in serum cholesterol i.e. (101% and 106%) and pyruvic acid increased significantly to a maximum value of 106% after 6 hrs of treatment at 40% LD50. Glycogen levels in the gastrocnemius muscle were found to decrease significantly (p-0.05) to 43% and 92% at LD50 after injection of purified Ropalidia marginata venom after 8 h and 80% at LD50 compared to control. Moreover, up to 71% and 81% were obtained at 10 hrs of treatment with the same dose. In the present study, the purified toxins significantly changed the levels of biomolecules in blood serum, indicating their wider effects on cellular physiology due to toxic effects and stress on the animal. These toxins can be good antigens and stimulate immune responses in experimental mice.

Global Challenges and Solutions in the Early Warning,Monitoring and Toxicity Assessment of Biotoxins in the Food and Feed Chain

There is a massive and urgent need to ensure safety and security of the food supply of the world´s growing population.However,global agriculture and food industries continue to be vulnerable to problems of contamination with biotoxins produced by plants,algae and particularly by fungi;with global warming and extreme weather events making the occurrence of these toxic metabolites even more unpredictable.In this paper we summarize the multidisciplinary,multi-sectoral complementary competencies needed to innovate in various scientific fields and approaches,so strongly needed to develop improved early warning,monitoring and toxicity assessment of biotoxins in the food and feed chain.These include big data approaches using satellite and drone images,portable monitoring devices and(combined)toxicity testing of(emerging)biotoxins using proteomics and transcriptomics.

Transfer of Paralytic Shellfish Toxins via Marine Food Chains:A Simulated Experiment

Objective To study the transfer of paralytic shellfish toxins （PST） using four simulated marine food chains： dinoflagellate Alexandrium tamarense→Artemia Artemia salina→Mysid shrimp Neomysis awatschensis; A. tamarense→N. awatschensis; A. tamarense→A, salina→Perch Lateolabrax japonicus; and A. tamarense→L, japonicus. Methods The ingestion of A. tamarense, a producer of PST, by L. japonicus, N. awatschensis, and A. salina was first confirmed by microscopic observation of A. tamarense cells in the intestine samples of the three different organisms, and by the analysis of Chl.a levels in the samples. Toxin accumulation in L. japonicus and N. awatschensis directly from the feeding on A. tamarense or indirectly through the vector of A. salina was then studied, The toxicity of samples was measured using the AOAC mouse bioassay method, and the toxin content and profile of A. tamarense were analyzed by the HPLC method. Results Both A. salina and N. awatschensis could ingest A. tamarense cells. However, the ingestion capability of A. salina exceeded that of N. awatschensis. After the exposure to the culture of A. tamarense （2 000 cells·mL^-1） for 70 minutes, the content of Chl.a in A. salina and N. awatschensis reached 0.87 and 0.024 μg.mg^-1, respectively. Besides, A. tamarense cells existed in the intestines of L. japonicus, N. awatschensis and A. salina by microscopic observation. Therefore, the three organisms could ingest A. tamarense cells directly. A. salina could accumulate high content of PST, and the toxicity of A. salina in samples collected on days 1, 4, and 5 of the experiment was 2.18, 2.6, and 2.1 MU.g^-1, respectively. All extracts from the samples could lead to death of tested mice within 7 minutes, and the toxin content in anemia sample collected on the 1st day was estimated to be 1.65×10 ^5 μg STX equal/individual. Toxin accumulation in L japonicus and N. awatschensis directly from the feeding on A. tamarense or indirectly from the vector ofA. salina was also studied. The mice injected with extracts from L japonicus and N. awatschensis samples that accumulated PST either directly or indirectly showed PST intoxication symptoms, indicating that low levels of PST existed in these samples. Conclusion Paralytic shellfish toxins can be transferred to L. japonicus, N. awatschensis, and A. salina from A. tamarense directly or indirectly via the food chains.

Co-expression of Clostridium perfringens α and ε Toxins and Their Immunogenicity

The genc CPA and ETX encoding α and e toxins were amplified from the standard strain C60-2 of type D Clostridium perfingens by PCR, and then they were inserted into pet-Duct-1 vecto, respectively for the construction of co-expression plasmid pETDoet-1-CPA-ETX. The co-expression plasmid was transformed into BL21 （DE3） competent cells, at and e toxins proteins were induced by IPTG before analysis by SDS-PAGE. As a result, both of α and e toxins were detected at 43 and 34 KU by western-blot. Mice immunized with the co-expressed α and e toxins proteins produced high titers of neutralizing antibodies in the serum, which protected the mice against the attack of type D C. perfringens culture filtrate. In addition, mice immunized with the produced co-expressed α and e toxins proteins showed significantly higher surviving rate than with ε toxins protein alone when infected with culture filtrate of type D C. perfringens . These results indicated that co-expression of α and e toxins proteins could be used as a new method to prepare vaccines against the pathogens of multiple serotypes.

Why do we study animal toxins?

Venom （toxins） is an important trait evolved along the evolutionary tree of animals. Our knowledges on venoms, such as their origins and loss, the biological relevance and the coevolutionary patterns with other organisms are greatly helpful in understanding many fundamental biological questions, i.e., the environmental adaptation and survival competition, the evolution shaped development and balance of venoms, and the sophisticated correlations among venom, immunity, body power, intelligence, their genetic basis, inherent association, as well as the cost-benefit and trade-offs of biological economy. Lethal animal envenomation can be found worldwide However, from foe to friend, toxin studies have led lots of important discoveries and exciting avenues in deciphering and fighting human diseases, including the works awarded the Nobel Prize and lots of key clinic therapeutics. According to our survey, so far, only less than 0.1% of the toxins of the venomous animals in China have been explored. We emphasize on the similarities shared by venom and immune systems, as well as the studies of toxin knowledge-based physiological toxin-like proteins/peptides （TLPs）. We propose the natural pairing hypothesis. Evolution links toxins with humans. Our mission is to find out the right natural pairings and interactions of our body elements with toxins, and with endogenous toxin-like molecules. Although, in nature, toxins may endanger human lives, but from a philosophical point of view, knowing them well is an effective way to better understand ourselves. So, this is why we study toxins.

Environmental and Health Effects Associated With Harmful Algal Bloom and Marine Algal Toxins in China

The frequency and scale of Harmful Algal Bloom (HAB) and marine algal toxin incidents have been increasing and spreading in the past two decades, causing damages to the marine environment and threatening human life through contaminated seafood. To better understand the effect of HAB and marine algal toxins on marine environment and human health in China, this paper overviews HAB occurrence and marine algal toxin incidents, as well as their environmental and health effects in this country. HAB has been increasing rapidly along the Chinese coast since the 1970s, and at least 512 documented HAB events have occurred from 1952 to 2002 in the Chinese mainland. It has been found that PSP and DSP toxins are distributed widely along both the northern and southern Chinese coasts. The HAB and marine algal toxin events during the 1990s in China were summarized, showing that the HAB and algal toxins resulted in great damages to local fisheries, marine culture, quality of marine environment, and human health. Therefore, to protect the coastal environment and human health, attention to HAB and marine algal toxins is urgently needed from the environmental and epidemiologicalview.

BLUE-GREEN ALGAE TOXINS AND LIVER CANCER

Microcystins (MCYSTs) isolated from blue-green algae,are hepatotoxic polypeptides.It will induce severe intrahepatic hemorrhage and liver necrosis at low concentrations in rats and mice.MCYST- LR is one of MCYSTs which consists of 2 variable L- amino acids(leucine and arginine),3 D-amino acids and 2 unusualamino acids(including Adda).MCYSTs bind to protein phosphatase 1 and 2A,and strongly inhibit their activities.The resultant increase of phosphoprotein was referred to be involved in tumor-promoting activity in liver.According to the above results and animal study,MCYST-LR is a potent liver tumor promoter.There were 9 positive from 30 samples of pond-ditch water in high endemic county-Haimen by high-peformance liquid chromatograph and 3 already confirmed by liquid chromograph/mass spectrometer.The quantities of MCYSTs were different between drinking water of liver cancer cases and controls groups.122±0.057and 0.072±0.044μg/200ml respectively) by ELISA. It is not easy to remove by conventional water treatment procedures.The relationship between MCYSTs and oncogenes and anti-oncogenes are under studying.

Comparative analysis of diverse toxins from a new pharmaceutical centipede,Scolopendra mojiangica

As the oldest venomous animals,centipedes use their venom as a weapon to attack prey and for protection.Centipede venom,which contains many bioactive and pharmacologically active compounds,has been used for centuries in Chinese medicine,as shown by ancient records.Based on comparative analysis,we revealed the diversity of and differences in centipede toxin-like molecules between Scolopendra mojiangica,a substitute pharmaceutical material used in China,and S.subspinipes mutilans.More than 6000 peptides isolated from the venom were identified by electrospray ionization-tandem mass spectrometry(ESI-MS/MS)and inferred from the transcriptome.As a result,in the proteome of S.mojiangica,246 unique proteins were identified:one in five were toxin-like proteins or putative toxins with unknown function,accounting for a lower percentage of total proteins than that in S.mutilans.Transcriptome mining identified approximately 10 times more toxin-like proteins,which can characterize the precursor structures of mature toxinlike peptides.However,the constitution and quantity of the toxin transcripts in these two centipedes were similar.In toxicity assays,the crude venom showed strong insecticidal and hemolytic activity.These findings highlight the extensive diversity of toxin-like proteins in S.mojiangica and provide a new foundation for the medical-pharmaceutical use of centipede toxin-like proteins.

Dinophysis caudata generated lipophilic shellfish toxins in bivalves from the Nanji Islands, East China Sea

A 12-month program of monitoring potentially toxic microalgae(that produce lipophilic shellfi sh toxins; LSTs) and their toxins in bivalves was conducted from April 2006 to March 2007 in the Nanji Islands, East China Sea. Two Dinophysis species, D. caudata and D. acuminata, were identifi ed, and D. caudat a was found to be the dominant species. D. caudata was detected in water samples between April and June 2006, and between February and March 2007. It reached its highest abundances in May, with a mean abundance of 1.38×10 2 cells/L in surface water and 1.25×10 2 cells/L in bottom water(<10 m deep). The temporal distribution of D. caudata was associated with the occurrence of LSTs in bivalve samples, which mostly occurred at the same time as D. caudata blooms, between April and July 2006. All of the cultured bivalves sampled between April and June were contaminated with LSTs, with an average toxicity of 85 μg okadaic acid(OA) eq./100 g meat, which was four times higher than the Chinese regulatory limit(20 μg OA eq./100 g meat). Ten out of fi fteen wild samples(66.7%) collected during the same period were positive for LSTs, and contained an average LST toxicity of 45 μg OA eq./100 g meat(more than twice the regulatory value). Cultured Patinopecten yessoensis collected on 15 May 2006 had the highest toxicity, 320 μg OA eq./100 g meat, and relatively high toxicities(80 to 160 μg OA eq./100 g meat) were found in bivalves until the end of July.

The inherent high vulnerability of dopaminergic neurons toward mitochondrial toxins may contribute to the etiology of Parkinson＇s disease

Although the exact mechanism（s）of the degeneration of dopaminergic neurons in Parkinson’s disease（PD）is not well understood,mitochondrial dysfunction is proposed to play a central role.This proposal is strongly strengthened by the findings that compromised mitochondrial functions and/or exposure to mitochondrial toxins such as rotenone,paraquat,or MPTP causes degeneration of the midbrain dopaminergic.

A Plasmonic Mass Spectrometry Approach for Detection of Small Nutrients and Toxins

Nutriology relies on advanced analytical tools to study the molecular compositions of food and provide key information on sample quality/safety. Small nutrients detection is challenging due to the high diversity and broad dynamic range of molecules in food samples, and a further issue is to track low abundance toxins. Herein, we developed a novel plasmonic matrix-assisted laser desorption/ionization mass spectrometry(MALDI MS)approach to detect small nutrients and toxins in complex biological emulsion samples. Silver nanoshells(SiO_2@-Ag) with optimized structures were used as matrices andachieved direct analysis of ~ 6 n L of human breast milk without any enrichment or separation. We performed identification and quantitation of small nutrients and toxins with limit-of-detection down to 0.4 pmol(for melamine) and reaction time shortened to minutes, which is superior to the conventional biochemical method currently in use. The developed approach contributes to the near-future application of MALDI MS in a broad field and personalized design of plasmonic materials for real-case bio-analysis.

Receptor variability-driven evolution of snake toxins

Three-finger toxins （TFTs） are well-recognized non- enzymatic venom proteins found in snakes. However, although TFTs exhibit accelerated evolution, the drivers of this evolution remain poorly understood. The structural complexes between long-chain α-neurotoxins, a subfamily of TFTs, and their nicotinic acetylcholine receptor targets have been determined in previous research, providing an opportunity to address such questions. In the current study, we observed several previously identified positively selected sites （PSSs） and the highly variable C-terminal loop of these toxins at the toxin/receptor interface. Of interest, analysis of the molecular adaptation of the toxin-recognition regions in the corresponding receptors provided no statistical evidence for positive selection. However, these regions accumulated abundant amino acid variations in the receptors from the prey of snakes, suggesting that accelerated substitution of TFTs could be a consequence of adaptation to these variations. To the best of our knowledge, this atypical evolution, initially discovered in scorpions, is reported in snake toxins for the first time and may be applicable for the evolution of toxins from other venomous animals.

Comparative study on in vitro transformation of paralytic shellfish poisoning (PSP) toxins in different shellfish tissues

Dissected tissues of three shellfish species, the Chinese scallop, Chlamys farreri, Manila clam, Ruditapes philippinarurn, and Razor shell, Solen strictu were evaluated for in vitro transformation of paralytic shellfish poisoning （PSP） toxins. Tissue homogenates were incubated with extraction from toxic algae Alexandriurn rninutura to determine toxin conversion. The effects of heating and addition of a natural reductant （glutathione） on toxin conversion were also assessed. The toxin profile was investigated through high performance liquid chromatography with fluorescence detection （HPLC-FLD）. The evident variations in the toxin content were observed only in Chinese scallop viscera homogenates. The concentration of GTX4 was reduced by 45% （approximately 0.8 μmol/dm^3） and 25% （approximately 1 μmol/dm^3） for GTX1, while GTX2 and GTX3 increased by six times （approximately 1 μmol/dm^3） and 3 times （approximately 0.3μmol/dm^3） respectively. Simultaneously, the total toxicity decreased by 38% during the 48 h incubation period, the final toxicity was 20.4 nmol STXeq/g. Furthermore, heated Chinese scallop viscera homogenates samples were compared with non-heated samples. The concentration of the GTX4 and GTX1 was clearly 28% （approximately 0.53 μmol/dm^3） and 17% （approximately 0.69μmol/dm^3） higher in heated samples, GTX2 and GTX3 were four times （0.66 μmol/dm^3） and two times （0.187 μmol/dm^3） lower respectively. GSH （＋） Chinese scallop viscera homogenates samples were compared with GSH （-） samples, the concentration in the GTX4 and GTX1 was 9% （approximately 0.12 μmol/dm^3） and 11% （approximately 0.36 μmol/dm^3） lower respectively, GTX2 and GTX3 was 17% （approximately 0.14 μmol/dm^3） and 19% （approximately 0.006 μmol/dm^3） higher respectively. In contrast,there was a little change in the concentration of PSP toxins of Manila clam and Razor shell tissue ho- mogenates. These observations on three shellfish tissues confirmed that there were species-specific differences in PSP toxins transformation. PSP toxins transformation was more pronounced in viscera tissue than in muscle tissue. PSP toxins was possibly interfered by some carbamoylase enzyme, and the activity in Chinese scallop viscera tissue is more remarkable than in the other two species.

Depuration of paralytic shellfish toxins in Japanese scallop(Patinopecten yessoensis) in natural environment

To study the paralytic shellfish toxins（PSTs） depuration in Japanese scallop Patinopecten yessoensis in natural environment, Japanese scallops naturally contaminated with paralytic shellfish poisoning（PSP） toxins in the Dayao Bay in the northern Huanghai Sea are transited to Qipanmo waters in the Bohai Sea of no reported PSTs incidents. The levels and profile of PSTs during 30-day depuration are detected by the high performance liquid chromatography with fluorescence detection（HPLC-FLD）. The results show that the toxicity of the PSTs in soft tissues decreases to a relatively low level at Day 9. Moreover, the depurated ratio at the early stage of the PSTs depuration is higher than that at the later stage. The toxicity analysis of dissected organs reveals that the digestive gland is the most contaminated PSTs part, which is of important implication for the human health and scallop aquiculture. The mortality of Japanese scallops during PSTs depuration experiment is relevant to PSTs level in the soft tissue.

Screening for lipophilic marine toxins and their potential producers in coastal waters of Weihai in autumn,2020

Lipophilic marine toxins(LMTs)produced by some microalgae in the sea could accumulate in shellfish and pose potential threats to the health of seafood consumers.Phytoplankton and shellfish samples were collected from coastal waters of Weihai in Shandong Peninsula,China in autumn,2020,and screened for lipophilic marine toxins and their potential producers using liquid chromatography-tandem mass spectrometry(LC-MS/MS)analysis and high throughput sequencing of partial DNA(V4 region of the 18S rRNA gene)extracted from phytoplankton.Pectenotoxin-2(PTX2),trace amounts of azaspiracid(AZA1 or AZA40),and 13-desmethyl spirolide C(13-DesMe-C)were detected in phytoplankton samples,while PTX2 and gymnodimine(GYM)were detected in shellfish samples.The toxin content in shellfish samples was much lower than the regulatory limit or values reported previously.Results suggest that lipophilic marine toxins should have low risk in coastal waters of Weihai in autumn.Based on the data of high throughput sequencing,the OTUs were assigned to 5 identified species of Alexandrium,including A.ostenfeldii capable of producing 13-DesMe-C and GYM.Two OTUs were found closely related to the toxic species in genus Dinophysis,but it is impossible to assign them to any identified species due to the low resolving power of the V4 region for Dinophysis.The OTUs could not be assigned to any identified species in the genus Azadinium,suggesting the existence of unidentified species in this region.

The“harmful algae and algal toxins in coastal waters of China:investigation and database”project

The“harmful algae and algal toxins in coastal waters of China:investigation and database”project(HAATC)is funded(US$2.3 million)by the Ministry of Science and Technology of China for 60 months starting on the 1st Jan 2019.Since the 1990s,national projects and other related work have greatly improved harmful algal bloom(HAB)research in China.However,the existing research on HABs is often limited to specific sea areas or specific algal bloom disasters,which is insufficient for understanding the long-term evolution of HAB occurrence under the influence of intensified human activity and global change.The HAATC project intends to determine the overall distribution of marine harmful microalgae and macroalgae,and marine algal toxins(in phytoplankton and shellfish)through a large-scale investigation in the coastal waters of China and continuous investigation in key sea areas.It also aims to observe biotic and abiotic processes during harmful red tides and green tides,and establish an open database and query platform of HABs in China.The research consortium,led by chief scientist Prof.Tian YAN,includes approximately 100 scientists and students.More than 2 years of work have shown the increased distribution of HAB species(including cysts)and algal toxins in China’s coastal waters,the increased occurrence of macroalgae blooms(mainly by Ulva prolifera and Sargassum horneri)in the Southern Yellow Sea,increased amount of causative species being identified due to the use of molecular technologies in taxonomy,and new records of algal toxins such as azaspiracid,cycloimines and neurotoxinsβ-N-methylamino-l-alanine have been detected,which complicates the research in algal toxins and toxicology.Eventually,the project will provide systematic basic data and techniques for the rapid and accurate identification of harmful algae species to support the research,monitoring,and control of harmful algal blooms,as well as seafood safety management in China.

Oxidative metabolism of photosynthetic species and the exposure to some freshwater and marine biotoxins

Environmental climate conditions could lead to an increasing global occurrence of microorganism blooms that synthesize toxins in the aquatic environments.These blooms could result in significantly toxic events.Responses of photosynthetic organisms to adverse environmental conditions implicate reactive oxygen species generation;but,due to the presence of a varied cellular antioxidant defense system and complex signaling networks,this oxidative stress could act as an important factor in the environmental adaptive processes.The objective of this review was to assess how some biotoxins are implicated in the generation of oxidative and nitrosative metabolic changes,not only in biotoxin-producing organisms but also in non-producing organisms.Therefore,toxins may modify the oxidative cellular balance of several other species.Hence,the effect of toxins on the oxidative and nitrosative conditions will be evaluated in freshwater and marine algae and vascular plants.The changing climate conditions could act as agents capable of modifying the community composition leading to alterations in the global health of the habitat,risking the survival of many species with ecological relevance.

Reporter Gene Assay for Detection of Shellfish Toxins

Objective To explore the potential reporter gene assay for the detection of sodium channel-specific toxins in shellfish as an alternative for screening harmful algal bloom (HAB) toxins, considering the fact that the existing methods including HPLC and bioassay are inappropriate for identifying HAB toxins which poses a serious problem on human health and shellfish industry. Methods A reporter plasmid pEGFP-c-fos containing c-fos promoter and EGFP was constructed and transfected into T24 cells using LipofectAMINE 2000. Positive transfcctants were screened by G418 to produce a pEGFP-c-fos-T24 cell line. After addition of increasing neurotoxic shellfish poison (NSP) or GTX2,3, primary components of paralytic shellfish poison (PSP), changes in expression of EGFP in the cell line were observed under a laser scanning confocal microscope and quantified with Image-pro Plus software. Results Dose-dependent changes in the intensity of green fluorescence were observed for NSP in a range from 0 to 10 ng/mL and for GTX2,3 from 0 to 16 ng/mL. Conclusion pEGFP-c-fos-T24 can be applied in detecting HAB toxins, and cell-based assay can be used as an alternative for screening sodium channel-specific HAB toxins.