| In recent decades,with the global climate change and the deterioration of the marine environment,the distribution of the paralytic shellfish poisoning(PSP)toxin-producing algae in the world is gradually expanding.The PSP toxins produced by the toxigenic algae are potent neurotoxic and easy to accumulate in the shellfish.They can be passed to humans via the food chain,which can cause muscle paralysis,dyspnea or even death in humans.To date,there are many studies on the distribution of PSP toxigenic algae and its sporocysts in Marine environment and the effects of environmental climate change on the intracellular accumulation of PSP toxins in PSP toxigenic algae.However,few studies have been conducted on the growth and extracellular release of PSP toxins from typical Marine toxigenic algae under the combined action of eutrophication and acidification.In this study,a new method was developed for the determination of common extracellular PSP toxins in the culture medium of toxigenic algae by using liquid chromatography-mass spectrometry(LC-MS),and Alexandrium minutum was used as the research object to investigate the growth and toxin production of it under eutrophication and acidified seawater conditions systematically by simulating the eutrophication and acidificed environment in the laboratory.The details are as follows:1.In this study,a reliable new method for the determination of six common PSP toxins in marine dinoflagellates extracellular culture medium of toxigenic algae was established by using GCB-SPE and HILIC-HRMS combined technology.Satisfactory absolute recoveries(87.5%-102.4%),precision(relative standard deviations(RSD)<7.6%),and linearity(R2>0.9998)were also achieved.Subsequently,the proposed method was applied to screen and detection the extracellular PSP toxins of A.minutum and A.tamarense.Over the whole growing period,the total concentration of four extracellular PSP toxins(GTX1,GTX2,GTX3,and GTX4)of A.minutum was within 2.9 ?g/L to 735.5 ?g/L and two extracellular PSP toxins(Cl and C2)of A.tamarense was within 3.0?g/L to 19.2 ?g/L.The concentrations of extracellular PSP toxins varied significantly in different growth stages of A.minutum and A.tamarense,and the contents of some extracellular PSP toxins were significantly higher than that of intracellular PSP toxins.The results showed that this method could provide a technical support for the characterization of the extracellular PSP toxins,and may offer a novel insight into the accumulation and release patterns of PSP toxins from marine dinoflagellates.2.The growth and toxin production of algae under different climate and environment changes were preliminary studied through indoor eutrophication and acidified seawater experiments.First,the effect of acidified environment on the growth and toxicity of A.minutum under eutrophication condition was investigated.The acidified environment could promote the growth,toxin-producing ability and toxicity of A.minutum with a certain degree.Meanwhile,the growth,chlorophyll a concentration,four PSP toxins content and composition in intracellular and extracellular culture medium of A.minutum as well as the ratio of PSP toxin content in extracellular culture medium to intracellular showed different trends with the decrease of the pH value of the culture medium.Secondly,the effect of eutrophication environment on the growth and toxin production of A.minutum under acidification condition was investigated.In the acidified environment,to a certain extent,the increase in the degree of eutrophication was not conducive to the growth of A.minutum,and it reduced the content of chlorophyll a and the phosphorus storage capacity of A minutum,however,there was no significant effect on the nitrogen absorption capacity ofA.minutum.Meanwhile,in the acidified environment,to a certain extent,the increase in the degree of eutrophication was conducive to the increase of the intracellular and extracellular PSP toxins content and toxicity of A.minutum. |
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