Study On The Accumulation And Elimination Law Of Thick-shelled Mussel (Mytilus Coruscus) On Field Soft Sponge Acid Toxins

Okadaic Acid(OA)and its derivatives(dinophysistoxins,DTXs)are common and widely distributed marine biological toxins.Related studies have proved their acute toxicity(diarrhea,vomiting,etc.)and chronic toxic effects.This paper summarizes recent progress of the OA toxins in the area of toxication mechanism,in vivo assay,cytotoxicity,genotoxicity,neurotoxicity and immunological toxicity,and provides a reference for further toxicology research of the toxins.In this paper,the extraction method of OA related toxins which was build in advance in our laboratory had been validated.The results showed that the target peaks of the chromatogram were symmetrical and sharp,and there were no impurity peaks nearby.The linearity of OA related toxins was good within 0.5-20 ng/mL,and the correlation coefficient was greater than 0.999.The method had high recovery,precision and sensitivity,which met the detection requirements of OA related toxins in subsequent experimental samples.The accumulation and elimination of OA related toxins in mussels and their tissues at different exposure time were studied by simulated indoor exposure experiments based on mussel and the method of immunoaffinity pretreatment and liquid chromatography-tandem mass spectrometry(LC-MS/MS):(1)In the short-term simulated indoor exposure experiment,the daily feeding level of P.lima was 5×10~4cells,P.lima produced only OA and DTX-1,with the single cell toxicity of 2.62±0.01 and 2.31±0.01 pg,respectively.The filtering rate of mussel decreased from 99.1%to 96.1%,and the conversion rate of OA and DTX-1 was48.3-59.3%and 48.5-61.4%,respectively.The target organ of OA related toxins is digestive gland,and the potential of each tissue to accumulate OA related toxins is digestive gland>gill>muscle>mantle>adductor.The potential of each tissue to eliminate OA related toxins toxin is gill>digestive gland>mantle>adductor>muscle.At the current feeding level,the toxin content in mussel body will be higher than 45 ng OA eq./g in only 10 days.The average accumulation and elimination rates of OA related toxins by mussel were 5.0 and 1.8 ng OA eq./g/day,respectively.The half-time of mussel to OA and DTX-1 were both 4.2 days.(2)In the long term simulated indoor exposure experiment,the daily feeding level of P.lima was 5×10~5cells,P.lima produced only OA and DTX-1,with the single cell toxicity of 3.94±0.01 and 3.44±0.01 pg,respectively.There were OA,DTX-1and DTX-3 in mussel,and the proportion of DTX-3 was 3.3-17.9%,the main toxin form is free form.The filtering rate of mussel decreased from 99.4%to 58.5%,and the conversion rate of OA and DTX-1 was 59.0-89.9%and 49.9-94.9%,respectively.The target organ of OA related toxins is digestive gland,and the potential of each tissue to accumulate OA related toxins is digestive gland>gill>muscle>mantle>adductor,the potential of each tissue to eliminate OA related toxins toxin is gill>adductor>muscle>digestive gland>mantle.On the third day of accumulation,the concentration of OA related toxins exceeded the safety limit of 160 ng OA eq./g,and on the seventh day of accumulation,the concentration reached 324.5 ng OA eq./g,twice the safety limit.The half-time of mussel to OA and DTX-1 were 27.1 and 20.3 days,respectively.It will take 42.8 days to make the concentration lower than 45 ng OA eq./g.(3)Comparing short term and long term simulated indoor exposure experiments,it can be find that P.lima only produces OA and DTX-1,but its toxicity level is not constant;The feeding level and duration of feeding days of P.lima not only affect the filtering rate of mussel,but also affect the conversion rate of OA and DTX-1;the digestive gland always maintains the fastest toxin accumulation rate and the largest toxin concentration.Tissues show the same accumulative capacity to OA related toxins,but the different ability to eliminate toxins between short term and long term.The daily feeding level of 5×10~4 cell is not enough to make mussel exceed the safety limit.If the feeding level is raised to 10 times of the original level,it will take only 3days for the OA related toxins concentration exceeds the safety limit.