Study On Screening Of LncRNA Biomarkers For Heavy Metal Pollutants

The toxic effects of heavy metal pollutants on humans and other organisms had received widespread attention.We used several typical environmental heavy metal pollutants,such as mercury chloride,lead acetate,potassium chromate,cadmium chloride and methyl mercury,to conduct exposure experiments on zebrafish embryos and detect the expression of lncRNAbirc6-as,malat1,mettl3,setd1baandoip5-as.We anticipate to screen out potential lncRNA biomarkers for heavy metal pollutants in zebrafish embryos.In this paper,zebrafish embryos were exposed to 96 hpf by treated with HgCl₂,Pb（CH₃COO）₂,K₂CrO₄,and CdCl₂ respectively.In the HgCl₂ treatment group,the expression of lncRNA malat1 was significantly increased and showed a dose-effect relationship with the concentration of HgCl₂,even up to high concentration（100 ppb）group increased 10.79 times.The expression levels of other lncRNA was not significantly changed.In other Pb（CH₃COO）₂,k₂CrO₄ and CdCl₂ treatment group,the change of lncRNA expression levels did not be observed.After screening lncRNA malat1,the expression of malat1 in zebrafish embryos was detected in 9 different stages from the 1-cell to 96 hpf.The results showed that the expression of malat1 gradually increased with the development of embryos.In zebrafish embryos in situ hybridization experiment,we detected the expression of malat1 and the location of malat1.The results showed that the expression of malat1 increased with the increase of the concentration of HgCl₂,and the location of malat1 was in the head of zebrafish larvae.The same results were found in Me Hg exposure group.In order to further explore the neurotoxic effects of mercury compounds,we observed the motion behavior of zebrafish larvae,which exposed to different concentration of HgCl₂ at 96 hpf.The results showed that the movement rate of zebrafish larvae significantly decreased after exposure to HgCl₂.The zebrafish movement rate in the light environment from 1.15 mm/s dropped to 0.61 mm/s and in the dark environment from 1.88 mm/s dropped to 1.26 mm/s.These results suggested that the zebrafish larvae neural development could be affected by HgCl₂.Subsequently,the expression of the nerve-related genes mbp,α1-tubulin,syn2 a and gfap was detected.The results showed that the expressions level of gafp and syn2 a was significantly down-regulated in the HgCl₂ treatment group and related to the concentration of HgCl₂.Compared with the control group,in the high concentration（100 ppb）group,the expressions level of gafp and syn2 a was down-regulated to 49/100 and 38/100,respectively.According to the experimental results,lncRNA malat1 was sensitive to HgCl₂ in zebrafish embryos,and it was expressed in the head,eyes and nervous system of zebrafish embryos.Mercury compounds had been widely recognized as neurotoxic substances,and the experiment results suggested that malat1 might be involved in the early neurodevelopment of zebrafish embryos,and played an important role in the neurotoxic mechanism of HgCl₂.Malat1 can be used as a potential biomarker of mercury compounds,but its specific molecular mechanism needs to be further verified.