食源亚历山大藻核糖体DNA分子特征及其产毒特性的遗传差异

Molecular Characteristics of Ribosome DNA and Genetic Difference of Toxigenic Characteristics of Food-Borne Alexandrium Strains

亚历山大藻可代谢产生麻痹性贝毒素,对人类健康和食品安全造成严重威胁。以核糖体DNA为研究对象,利用生物信息学及计算机分析软件对食源亚历山大藻核糖体DNA的分子特征进行分析,并且对亚历山大藻的产毒特性进行遗传差异研究。聚合酶链式反应（polymerase chain reaction,PCR）扩增亚历山大藻核糖体18S r DNA-28S r DNA区域,利用DNAdist计算5.8S r DNA-ITS区域序列间距离值序数,同时,利用PCR-限制性片段长度多态性（restricted fragment length polymorphisms,RFLP）技术,对核糖体18S r DNA-28S r DNA进行测序分析,选择限制性内切酶MboⅡ绘制内切酶图谱。结果表明：亚历山大藻无毒株L35与产毒株在5.8S r DNA-ITS区域序列间核苷酸的差异值可达到0.201~0.488,与同属无毒亚历山大藻的核苷酸差异值〈0.004;通过酶切图谱特征条带可以准确地将不同亚历山大藻种产毒类型分3类,酶切图谱相似的藻种产生的毒素组分相同。因此,食源亚历山大藻产毒与否以及产毒类型体现为核糖体DNA遗传信息中存在显著差异。

Paralytic shellfish poisoning could be caused by the toxin produced by Alexandrium strains, which seriouslythreatens human health and food safety. Molecular characteristics of ribosome DNA and toxic characteristics of foodborneAlexandrium species were analyzed by bioinformatics and computer analysis software. The 18S rDNA–28S rDNAregion was amplified by PCR method, and 5.8S rDNA-ITS region was calculated by using DNAdist program. Moreover, the18S rDNA–28S rDNA region was sequenced by PCR restricted fragment length polymorphisms （RFLP） method, and Mbo II wasselected for restriction endonuclease mapping. The results showed that nucleotide sequence differences in the 5.8S rDNA-ITSregion between non-toxic strain Alexandrium L35 and toxic strains could reach 0.201–0.448, while values 〈 0.004 werenoted among non-toxin strains. Toxin could be distinguished into three types by the characteristic bands of endonucleasemap, and toxin components were same if strains had similar endonuclease map. Hence toxin production ability and toxintypes of Alexandrium strains reflected significant genetic differences in ribosome DNA.