15N stable isotope labeling PSTs in alexandrium minutum for application of PSTs as biomarker

Abstract

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 with15N stable isotope to obtain15N-PSTs instead of original14N, 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 different15N/P concentrations. The15N-PSTs’ toxicity and toxin profile were detected. Meanwhile, the15N labeling abundance and15N atom number of15N-PSTs were identified. The14N of PSTs produced by A. minutum can be successfully replaced by15N, and the f/2 medium of standard15N/P concentration was the best choice in terms of the species’ growth, PST profile,15N labeling result and experiment cost. After many (>15) generations, the15N abundance in PSTs extract reached 82.36%, and the15N atom number introduced into GTX1-4 might be 4-6. This paper innovatively provided the initial evidence that15N isotope application of labeling PSTs in A. minutum is feasible. The15N-PSTs as biomarker can be applied and provide further information on PSTs metabolism.