Functional genomics of a non-toxic Alexandrium lusitanicum culture

摘要

Paralytic shellfish poisoning (PSP) is a human intoxication associated with the consumption of shellfish contaminated with a family of neurotoxins called saxitoxins. Many species in the dinoflagellate genus Alexandrium have been shown to produce these toxins. Here I report the first case of a culture of Alexandrium that has completely lost the ability to produce saxitoxins. The loss of toxicity was accompanied by a reduction in growth capability. A subculture of this isolate maintains the ability to produce toxins and to grow at rates and to cell abundances that were characteristic of the original Alexandrium culture. The growth and toxicity differences in the two isolates were demonstrated to be a property of the dinoflagellate itself and were not dependent on the different bacterial symbionts associated with each culture. The pair of subcultures is a novel experimental system to study gene expression related to toxin production and growth in dinoflagellates. The products of gene expression were analyzed in the two subcultures of Alexandrium grown under the same conditions, but where toxicity and growth differ. At the metabolome level, compounds were identified that were unique to the non-toxic isolate; their emergence may be correlated to a disruption of the biosynthetic pathway for PSP toxins.