Influence of nitrogen availability on the expression of genes involved in the biosynthesis of saxitoxin and analogs in Cylindrospermopsis raciborskii

Vico, Paula; Aubriot, Luis; Martigani, Fátima; Rigamonti, Natalia; Bonilla, Sylvia; Piccini, Claudia

doi:10.1016/j.hal.2016.04.008

Cited by 22 publications

(5 citation statements)

References 53 publications

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“…The increased glycolytic activity during phosphorus deficiency in A. minutum may also result in the production of more acetyl-CoA and malonyl-CoA molecules, which are required to initiate saxitoxin biosynthesis. Under nitrogen deficiency, the low rate of saxitoxin biosynthesis is indirectly influenced by a decrease in cellular growth rate [ 89 , 90 ]. Additionally, during nitrogen deficiency, acetyl-CoA is redirected towards fatty acid synthesis, thereby reducing the pool of precursors available for saxitoxin biosynthesis in A. minutum .…”

Section: Resultsmentioning

confidence: 99%

Nutrient Deficiencies Impact on the Cellular and Metabolic Responses of Saxitoxin Producing Alexandrium minutum: A Transcriptomic Perspective

Akbar,

Mohd Yusof,

Usup

et al. 2023

Marine Drugs

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Dinoflagellate Alexandrium minutum Halim is commonly associated with harmful algal blooms (HABs) in tropical marine waters due to its saxitoxin production. However, limited information is available regarding the cellular and metabolic changes of A. minutum in nutrient-deficient environments. To fill this gap, our study aimed to investigate the transcriptomic responses of A. minutum under nitrogen and phosphorus deficiency. The induction of nitrogen and phosphorus deficiency resulted in the identification of 1049 and 763 differently expressed genes (DEGs), respectively. Further analysis using gene set enrichment analysis (GSEA) revealed 702 and 1251 enriched gene ontology (GO) terms associated with nitrogen and phosphorus deficiency, respectively. Our results indicate that in laboratory cultures, nitrogen deficiency primarily affects meiosis, carbohydrate catabolism, ammonium assimilation, ion homeostasis, and protein kinase activity. On the other hand, phosphorus deficiency primarily affects the carbon metabolic response, cellular ion transfer, actin-dependent cell movement, signalling pathways, and protein recycling. Our study provides valuable insights into biological processes and genes regulating A. minutum’s response to nutrient deficiencies, furthering our understanding of the ecophysiological response of HABs to environmental change.

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Section: Resultsmentioning

confidence: 99%

Nutrient Deficiencies Impact on the Cellular and Metabolic Responses of Saxitoxin Producing Alexandrium minutum: A Transcriptomic Perspective

Akbar,

Mohd Yusof,

Usup

et al. 2023

Marine Drugs

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“…These genes are reliable markers for assessing STX synthesis because they encode enzymes that participate in key steps of STX formation. Other studies have successfully used these sxt molecular markers as reporters to assess STX biosynthesis in R. raciborskii [65,66]. Yang et al [64] were the first to demonstrate an increased cellular toxin content and associated transcript profile of a STX-producing dinoflagellate exposed to zooplankton cues, although no genes of the sxt cluster were identified.…”

Section: Discussionmentioning

confidence: 99%

“…Although most steps in the biosynthesis pathway of STX are putative, sequence similarity analysis indicates that the sxtU gene encodes a dehydrogenase that reduces the terminal aldehyde group of the STX precursor [60], and the sxtI gene encodes a carbamoyltransferase that catalyzes carbamoyl transfer from carbamoyl phosphate onto the free hydroxyl at C-13, forming STX. We chose these genes based on previous studies that reported a coherent response pattern of sxtI and sxtU and the other genes of the sxt cluster, and a coherent response of sxtI and sxtU expression and STX levels [65,66]. The reference gene used to calculate the relative expression of the target genes was rpoC1, which encodes the RNA polymerase gamma subunit [99].…”

Section: Expression Of Genes Involved In Stx Biosynthesismentioning

confidence: 99%

Ecophysiological Aspects and sxt Genes Expression Underlying Induced Chemical Defense in STX-Producing Raphidiopsis raciborskii (Cyanobacteria) against the Zooplankter Daphnia gessneri

Vilar

Rodrigues

Silva

et al. 2021

Toxins

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Cyanobacteria stand out among phytoplankton when they form massive blooms and produce toxins. Because cyanotoxin genes date to the origin of metazoans, the hypothesis that cyanotoxins function as a defense against herbivory is still debated. Although their primary cellular function might vary, these metabolites could have evolved as an anti-predator response. Here we evaluated the physiological and molecular responses of a saxitoxin-producing Raphidiopsis raciborskii to infochemicals released by the grazer Daphnia gessneri. Induced chemical defenses were evidenced in R. raciborskii as a significant increase in the transcription level of sxt genes, followed by an increase in saxitoxin content when exposed to predator cues. Moreover, cyanobacterial growth decreased, and no significant effects on photosynthesis or morphology were observed. Overall, the induced defense response was accompanied by a trade-off between toxin production and growth. These results shed light on the mechanisms underlying zooplankton–cyanobacteria interactions in aquatic food webs. The widespread occurrence of the cyanobacterium R. raciborskii in freshwater bodies has been attributed to its phenotypic plasticity. Assessing the potential of this species to thrive over interaction filters such as zooplankton grazing pressure can enhance our understanding of its adaptive success.

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“…In spite of the fact that the ecological role of cyanotoxins remains unknown (Neilan et al, 2013), environmental factors such as nutrients, light, and temperature have been proposed to cause a potential impact on toxins production (Holland & Kinnear, 2013). Nitrogen depletion, light intensity, and UV-B exposure appear to be key factors that influence STX production (Carneiro et al, 2009;Casero et al, 2014;Beamud et al, 2015), while other studies revealed no nutrient effect on its production (Stucken et al, 2014;Vico et al, 2016). It has been proposed that toxin production could confer ecological advantages to toxic strains (Holland & Kinnear, 2013).…”

Section: Discussionmentioning

confidence: 99%

Synergistic effects of nutrients and light favor Nostocales over non-heterocystous cyanobacteria

et al. 2017

Self Cite

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Blooms of Nostocales (Cyanobacteria) are thought to be invading subtropical and temperate water bodies. According to nutrient stoichiometry and physiological differences between cyanobacterial groups, the replacement of non-heterocystous species by Nostocales is favored when dissolved inorganic nitrogen decreases. However, some studies have shown different trends. We used laboratory bioassays to evaluate the concomitant effects of light and nutrient enrichment on phytoplankton assemblages dominated by non-heterocystous filamentous cyanobacteria. Three nutrient conditions (no addition, addition of phosphate, and addition of nitrate and phosphate) and two light intensities (40 and 80 lmol photon m -2 s -1 ) were assayed. Nostocales replaced or co-dominated with non-heterocystous species in all treatments by the end of the study. The shift in community composition towards Nostocales dominance led to an increase in species richness, which suggests that species with different eco-physiological traits may have differential impacts on diversity. The highest saxitoxin concentrations were measured in no addition treatments, which could link production to nutritional stress. Nostocales featured high phenotypic plasticity in terms of changes in average trichome Handling editor: Boping Han

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Influence of nitrogen availability on the expression of genes involved in the biosynthesis of saxitoxin and analogs in Cylindrospermopsis raciborskii

Cited by 22 publications

References 53 publications

Nutrient Deficiencies Impact on the Cellular and Metabolic Responses of Saxitoxin Producing Alexandrium minutum: A Transcriptomic Perspective

Nutrient Deficiencies Impact on the Cellular and Metabolic Responses of Saxitoxin Producing Alexandrium minutum: A Transcriptomic Perspective

Ecophysiological Aspects and sxt Genes Expression Underlying Induced Chemical Defense in STX-Producing Raphidiopsis raciborskii (Cyanobacteria) against the Zooplankter Daphnia gessneri

Synergistic effects of nutrients and light favor Nostocales over non-heterocystous cyanobacteria

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