石房蛤毒素致突变性研究

Study on mutagenicity of saxitoxin

目的通过Ames实验以及体外哺乳类细胞染色体畸变实验探索石房蛤毒素是否存在致突变性。方法通过Ames实验,选用组氨酸营养缺陷型鼠伤寒沙门氏菌TA97、TA98、TA100、TA102菌株,经过菌株鉴定及菌株毒性实验,在有、无代谢活化系统存在的情况下分别对石房蛤毒素以每皿0.04、0.2、1.0μg 3个剂量组进行实验,了解其是否具有致突变性。通过体外哺乳类细胞染色体畸变实验,采用MTT法检测石房蛤毒素对CHL细胞毒性,依据IC50确定实验剂量后染毒,制片、吉姆萨染色,镜下观察染色体畸变数量及类型,计算畸变率,评价其致突变性。结果在有、无S9活化系统条件下,在每皿0.04、0.2、1.0μg测试浓度范围内,石房蛤毒素对测试菌株诱发产生的回变菌落数未达到溶剂对照组回变菌落数的2倍,且无剂量反应关系。石房蛤毒素对CHL细胞毒性测定结果显示,有S9时,其IC50值为1.20 mg/mL;无S9时,其IC50值为1.34 mg/mL。石房蛤毒素对CHL细胞染色体畸变作用的研究结果显示,各剂量组分别在加入S9混合液和未加S9混合液条件下染色体畸变数及畸变率与阳性对照组比较,存在显著性差异(P<0.05);与阴性对照组比较,均无显著性差异(P>0.05)。结论在该实验条件下,石房蛤毒素未见致突变性。

Objective To explore the mutagenicity of saxitoxin by Ames test and in vitro mammalian chromosome aberration test.Methods After strain identification and toxicity tests,three dose groups of scorpion toxins 0.04,0.2 and 1.0μg/dish were tested in the presence or absence of a metabolic activation system by selecting histidine auxotrophic Salmonella typhimurium strains TA97,TA98,TA100 and TA102 through Ames test for studying the mutagenicity of saxitoxins.Toxicity of saxitoxin to CHL cells was detected using in vitro mammalian cell chromosome aberration test by MTT assay.According to IC50,identification of the test dose,exposure,tableting and Giemsa staining,the number and type of chromosome aberrations were observed under the microscope,the distortion rate was calculated,and the mutagenicity was evaluated.Results In the presence or absence of the S9 activation system,the number of reverting colonies induced by the test strains was not twice as high as that of the solvent control group with the test concentration range of 0.04,0.2 and 1.0μg/dish,respectively.There was no dose-response relationship.The results of cytotoxicity of scorpion toxin on CHL showed that the IC50 value is 1.20 mg/mL with the presence of S9 and the IC50 value is 1.34 mg/mL with the absence of S9.The results of the chromosomal aberration of CHL cells by Shifang toxin showed that there was a significant difference(P<0.05)of the number of chromosome aberrations and the aberration rate of each dose group comparing with the positive control group in the presence or absence of the S9 activation system.And compared with the negative control group,there was no significant difference(P>0.05).Conclusion Under the conditions of this experiment,the saxitoxin was not mutagenic.