De novo Transcriptome of the Non-saxitoxin Producing Alexandrium tamutum Reveals New Insights on Harmful Dinoflagellates

Abstract

Many dinoflagellates species, especially of the Alexandrium genus, produce a series of toxins with tremendous impacts on human and environmental health, and tourism economies. Alexandrium tamutum was discovered for the first time in the Gulf of Naples, and it is not known to produce saxitoxins. However, a clone of A. tamutum from the same Gulf showed copepod reproduction impairment and antiproliferative activity. In this study, the full transcriptome of the dinoflagellate A. tamutum is presented in both control and phosphate starvation conditions. RNA-seq approach was used for in silico identification of transcripts that can be involved in the synthesis of toxic compounds. Phosphate starvation was selected because it is known to induce toxin production for other Alexandrium spp. Results showed the presence of three transcripts related to saxitoxin synthesis (sxtA, sxtG and sxtU), and others potentially related to the synthesis of additional toxic compounds (e.g., 44 transcripts annotated as “polyketide synthase”). These data suggest that even if this A. tamutum clone does not produce saxitoxins, it has the potential to produce toxic metabolites, in line with the previously observed activity. These data give new insights into toxic microalgae, toxin production and their potential applications for the treatment of human pathologies.

Recent Progress in the Study of Peroxiredoxin in the Harmful Algal Bloom Species Chattonella marina

“…Comprehensive analysis of growth-phase-dependent gene expression will provide useful information about the molecular mechanisms that maintain growth potential and the molecular indicators that are candidates for monitoring growth potential in C. marina . Recently, RNA-seq analysis has been performed on harmful algae [ 34 , 35 , 36 , 38 ]. In our current study, RNA-seq analysis is being performed using C. marina cells in the exponential phase as well as the early-, mid-, and late-stationary phases of growth (manuscript in preparation).…”

“…Understanding the physiological mechanisms that allow algae to tolerate these environmental conditions is important to biological and fisheries science. Recently, omics analysis has begun to be used to investigate the comprehensive molecular mechanisms that account for HAB phenomena [ 21 , 33 , 34 , 35 , 36 , 37 , 38 ]. Our studies have focused on the molecular mechanisms that control the growth of HAB species.…”

Metagenomic characterization of planktonic communities during a mucilage event in the Çanakkale Strait (Dardanelles), Turkey

“…In the present study conducted in May 2021, when intense mucilage was observed, the dominant group was found to be the Alexandrium genus. Among many dinoflagellate species, the Alexandrium genus, in particular, produces toxins resulting in problems on human and environmental health as well as tourism economies (Vingiani et al, 2020). It was reported that Alexandrium species have the capability to produce mucilage and lead to shrimp and fish mortality in regions with algae bloom (Landsberg et al, 2002;Lewis et al, 2018).…”

Insights into Alexandrium minutum Nutrient Acquisition, Metabolism and Saxitoxin Biosynthesis through Comprehensive Transcriptome Survey

“…The transcriptomic approach is an ideal and holistic approach to analyze the mRNA sequences expressed by cells at specific times and conditions. There are existing transcriptomic data of several dinoflagellate species contributing to the phenomenon of HABs including both toxic ( Alexandrium minutum , Alexandrium fundyense , Alexandrium catenella , Prorocentrum minimum and Karenia brevis ) and non-toxic ( Alexandrium tamutum , Prorocentrum donghaiense , Scrippsiella trochoidea , Cochlodinium polykrikoides , Amphidinium carterae , Prorocentrum micans ) strains have been reported using transcriptomic approach via next-generation sequencing platform [ 3 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. These studies have allowed the discovery of dinoflagellates’ response toward stressors and determining putative genes responsible for toxin biosynthesis.…”