15N Stable Isotope Labeling PSTs in Alexandrium minutum for Application of PSTs as Biomarker

摘要

The dinoflagellate Alexandrium minutum (A. minutum) which can produce paralytic shellfish toxins (PSTs) is often used as a model to study the migration, biotransformation, accumulation, and removal of PSTs. However, the mechanism is still unclear. To provide a new tool for related studies, we tried to label PSTs metabolically with ¹⁵N stable isotope to obtain ¹⁵N-PSTs instead of original ¹⁴N, which could be treated as biomarker on PSTs metabolism. We then cultured the A. minutum AGY-H46 which produces toxins GTX1-4 in f/2 medium of different ¹⁵N/P concentrations. The ¹⁵N-PSTs’ toxicity and toxin profile were detected. Meanwhile, the ¹⁵N labeling abundance and ¹⁵N atom number of ¹⁵N-PSTs were identified. The ¹⁴N of PSTs produced by A. minutum can be successfully replaced by ¹⁵N, and the f/2 medium of standard ¹⁵N/P concentration was the best choice in terms of the species’ growth, PST profile, ¹⁵N labeling result and experiment cost. After many (>15) generations, the ¹⁵N abundance in PSTs extract reached 82.36%, and the ¹⁵N atom number introduced into GTX1-4 might be 4–6. This paper innovatively provided the initial evidence that ¹⁵N isotope application of labeling PSTs in A. minutum is feasible. The ¹⁵N-PSTs as biomarker can be applied and provide further information on PSTs metabolism.