Abstract
Paralytic shellfish toxins (PSTs), a group of neurotoxic alkaloids, are the most potent biotoxins for aquatic ecosystems and human health. Marine dinoflagellates and freshwater cyanobacteria are two producers of PSTs. The biosynthesis mechanism of PSTs has been well elucidated in cyanobacteria; however, it remains ambiguous in dinoflagellates. Here, we compared the transcriptome profiles of a toxin-producing dinoflagellate Alexandrium catenella (ACHK-T) at different toxin biosynthesis stages within the cell cycle using RNA-seq. The intracellular toxin content increased gradually in the middle G1 phase and rapidly in the late G1 phase, and then remained relatively stable in other phases. Samples from four toxin biosynthesis stages were selected for sequencing, and finally yielded 110,370 unigenes, of which 66,141 were successfully annotated in the known databases. An analysis of differentially expressed genes revealed that 2866 genes altered significantly and 297 were co-expressed throughout the four stages. These genes participated mainly in protein metabolism, carbohydrate metabolism, and the oxidation-reduction process. A total of 138 homologues of toxin genes were identified, but they altered insignificantly among different stages, indicating that toxin biosynthesis might be regulated translationally or post-translationally. Our results will serve as an important transcriptomic resource to characterize key molecular processes underlying dinoflagellate toxin biosynthesis.
Highlights
Dinoflagellates are important primary producers in marine ecosystems, and major causative agents producing paralytic shellfish toxins (PSTs) [1]
Cells of ACHK-T completed a whole cell cycle within 24 h (Figure 1A): the cells stayed in the G2/M phase when the light was turned on at T1 (08:00), followed by entering the G1 phase at T2 (10:00), and this phase lasted for 16 h until T10 (02:00) on the day
The results of the high-performance liquid chromatography (HPLC) analysis showed that the intracellular toxin content differed significantly (p < 0.05), and presented two increasing periods: a slow increase during the light period and a rapid enhancement 2 h after the dark period, which started at T8 (22:00)
Summary
Dinoflagellates are important primary producers in marine ecosystems, and major causative agents producing paralytic shellfish toxins (PSTs) [1]. Comprising saxitoxin (STX) and its recorded 57 analogs, PSTs act as the most potent and selective voltage-gated sodium channel blockers [2,3] They can cause human neural system syndromes, occasionally even death, and lead to approximately 2000 toxicosis cases annually worldwide [4]. With a length ranging from 25.7 kb to 36 kb, the clusters encode 24 to 32 proteins that participate in toxin biosynthesis [9]. Integrating their functions and the intermediates produced by each reaction, the biosynthesis pathway is proposed and refined in cyanobacteria [5,7,9]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
