Metabolomic study of saxitoxin analogues and biosynthetic intermediates in dinoflagellates using 15 N-labelled sodium nitrate as a nitrogen source

Yuko Cho, Shigeki Tsuchiya, Takuo Omura, Kazuhiko Koike, Hiroshi Oikawa, Keiichi Konoki, Yasukatsu Oshima, Mari Yotsu-Yamashita

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7 Citations (Scopus)

Abstract

A stable-isotope-labelling method using 15 N-labelled sodium nitrate as a nitrogen source was developed for the toxic dinoflagellate Alexandrium catenella. The labelled saxitoxin analogues (STXs), their precursor, and the biosynthetic intermediates were analyzed by column-switching high-resolution hydrophilic interaction liquid chromatography with mass spectrometry. The low contents on Day 0, high 15 N incorporation % of Int-C’2 and Int-E’ suggested that their turn-over rates are high and that the sizes of the pool of these compounds are smaller than those of the other intermediates. The experimentally determined isotopomer distributions showed that arginine, Int-C’2, 11-hydroxy-Int-C’2, Int-E’, GTX5, GTX4, C1, and C2, each existed as a combination of three populations that consisted of the non-labelled molecules and the labelled isotopomers representing molecules newly synthesized by incorporation of 15 N assimilated from the medium with two different incorporation rates. The order of 15 N incorporation % values of the labelled populations predicted by this model largely agreed with the proposed biosynthetic route. The stable-isotope-labelling method will be useful for understanding the complex mechanism of nitrogen flux in STX-producing dinoflagellates.

Original languageEnglish
Article number3460
JournalScientific reports
Volume9
Issue number1
DOIs
Publication statusPublished - 2019 Dec 1

ASJC Scopus subject areas

  • General

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