Abstract:

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

Key words: Alexandrium, nucleic acid sequences, toxins, molecular biology