Pseudo-nitzschia, Nitzschia, and domoic acid: New research since 2011

Bates, Stephen S.; Hubbard, Katherine A.; Lundholm, Nina; Montresor, Marina; Leaw, Chui Pin

doi:10.1016/j.hal.2018.06.001

Cited by 289 publications

(300 citation statements)

References 339 publications

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“…We did not detect any deterrence against grazing due to the algal toxin, the copepods ingested the same amounts of toxic and nontoxic diet in all experiments. This finding is supported by most studies conducted on copepod grazing on DA (Turner ; Bates et al 2018). The lack of response might be due to local adaption to the toxins, because the study organisms originated from the same locality and the Calanus spp.…”

Section: Discussionsupporting

confidence: 69%

“…The levels of DA in copepods will likely reflect a variation similar to the huge variation of cellular toxicity in Pseudo‐nitzschia during blooms (Fernandes et al ; Louw et al ). The cell concentrations used in the experiments and the toxin contents measured in Pseudo‐nitzschia are in the higher end of what has been found in the field, but is definitely not unrealistic (Bates et al 2018).…”

Section: Discussionmentioning

confidence: 77%

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Trophic interactions, toxicokinetics, and detoxification processes in a domoic acid‐producing diatom and two copepod species

Harðardóttir

Hjort

Wohlrab

et al. 2018

Limnology & Oceanography

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In costal ecosystems, copepods coexist with toxin-producing phytoplankton. The presence of copepods can amplify the phytoplankton toxin production and thereby increase the overall toxicity of a bloom. Copepods are not always affected by the toxins and can vector the toxins to higher trophic levels. To investigate the interactions between toxin producers and their grazers, we determined the kinetics of grazer-induced increases in toxin production and the subsequent toxin reduction in a domoic acid (DA)-producing diatom, Pseudo-nitzschia seriata. The cellular DA level of the diatom was within the range of in situ measurements. Ten days after removal of the copepods, 28% AE 8% of the cellular DA still remained in the cells. Simultaneously, we monitored the toxicokinetics of DA in two grazers; Calanus finmarchicus and Calanus glacialis. After 144 h of grazing on the toxic diet, the copepods accumulated and retained high concentrations of DA. Nine hours after exposure to the toxic diet was terminated, the copepods had depurated 70% AE 10% of the DA. The depuration lasted 4 AE 2 d and was independent of Calanus species and treatment. We explored the possible physiological responses in copepods after feeding on a purely toxic diet from gene expression profiles of C. finmarchicus. Expression of genes regulating several major metabolic and cellular processes was reduced in copepods feeding on DA-containing diatoms, and we hypothesize that this is because of exposure to DA.

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Section: Discussionsupporting

confidence: 69%

Section: Discussionmentioning

confidence: 77%

Trophic interactions, toxicokinetics, and detoxification processes in a domoic acid‐producing diatom and two copepod species

Harðardóttir

Hjort

Wohlrab

et al. 2018

Limnology & Oceanography

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“…Pseudo-nitzschia was demonstrated to be a source of DA already in 1988, but the ecological role of toxin production is still not fully understood. Pseudo-nitzschia cells react to several abiotic and biotic environmental factors such as changes in light, temperature, salinity, pH, pCO 2 and nutrient levels, as well as to the presence of bacteria and grazers by changing the production of toxins [16,17].…”

Section: Introductionmentioning

confidence: 99%

Transcriptomic responses to grazing reveal the metabolic pathway leading to the biosynthesis of domoic acid and highlight different defense strategies in diatoms

et al. 2019

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Background A major cause of phytoplankton mortality is predation by zooplankton. Strategies to avoid grazers have probably played a major role in the evolution of phytoplankton and impacted bloom dynamics and trophic energy transport. Certain species of the genus Pseudo-nitzschia produce the neurotoxin, domoic acid (DA), as a response to the presence of copepod grazers, suggesting that DA is a defense compound. The biosynthesis of DA comprises fusion of two precursors, a C10 isoprenoid geranyl pyrophosphate and l -glutamate. Geranyl pyrophosphate (GPP) may derive from the mevalonate isoprenoid (MEV) pathway in the cytosol or from the methyl-erythritol phosphate (MEP) pathway in the plastid. l -glutamate is suggested to derive from the citric acid cycle. Fragilariopsis , a phylogenetically related but nontoxic genus of diatoms, does not appear to possess a similar defense mechanism. We acquired information on genes involved in biosynthesis, precursor pathways and regulatory functions for DA production in the toxigenic Pseudo-nitzschia seriata , as well as genes involved in responses to grazers to resolve common responses for defense strategies in diatoms. Results Several genes are expressed in cells of Pseudo-nitzschia when these are exposed to predator cues. No genes are expressed in Fragilariopsis when treated similarly, indicating that the two taxa have evolved different strategies to avoid predation. Genes involved in signal transduction indicate that Pseudo-nitzschia cells receive signals from copepods that transduce cascading molecular precursors leading to the formation of DA. Five out of seven genes in the MEP pathway for synthesis of GPP are upregulated, but none in the conventional MEV pathway. Five genes with known or suggested functions in later steps of DA formation are upregulated. We conclude that no gene regulation supports that l -glutamate derives from the citric acid cycle, and we suggest the proline metabolism to be a downstream precursor. Conclusions Pseudo-nitzschia cells, but not Fragilariopsis , receive and respond to copepod cues. The cellular route for the C10 isoprenoid product for biosynthesis of DA arises from the MEP metabolic pathway and we suggest proline metabolism to be a downstream precursor for l -glutamate. We suggest 13 genes with unknown function to be involved in diatom responses to grazers. Electronic supplementary material The online version of this article (10.1186/s12867-019-0124-0) contains supplementary material, which is available to authorized users.

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“…The toxigenic species are responsible for amnesic shellfish poisoning (ASP) events worldwide (Bates et al. ). The symptoms of such intoxications are characterized by nausea, vomiting, abdominal cramps, diarrhea, short‐term memory loss, seizures, disorientation and in extreme cases, coma and death (Pulido , Ramsdell and Gulland , Schwarz et al.…”

mentioning

confidence: 99%

“…, Bates et al. ). This expansion is likely associated with the accentuated effects of climate change and anthropogenic activities in aquatic ecosystems (Durack and Wijffels , Skliris et al.…”

mentioning

confidence: 99%

Acclimation of the Marine Diatom Pseudo‐nitzschia australis to Different Salinity Conditions: Effects on Growth, Photosynthetic Activity, and Domoic Acid Content¹

Ayache

Hervé

Lundholm

et al. 2019

Journal of Phycology

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Toxic Pseudo-nitzschia australis strains isolated from French coastal waters were studied to investigate their capacity to adapt to different salinities. Their acclimation to different salinity conditions (10, 20, 30, 35, and 40) was studied on growth, photosynthetic capacity, cell biovolume, and domoic acid (DA) content. The strains showed an ability to acclimate to a salinity range from 20 to 40, with optimal growth rates between salinities 30 and 40. The highest cell biovolume was observed at the lowest salinity 20 and was associated with the lowest growth rate. Salinity did not affect the photosynthetic activity; F v /F m values and the pigment contents remained high with no significant difference among salinities. An enhanced production of zeaxanthin was, however, observed in the late stationary and decline phases in all cultures except for those acclimated to salinity 20. In terms of cellular toxin content, DA concentrations were 2 to 3-fold higher at the lowest salinity (20) than at the other salinities and were combined with a low amount of dissolved DA. The fact that P. australis accumulate more DA per cell in less saline waters, illustrates that climate-related changes in salinity may affect Pseudo-nitzschia physiology through direct effects on growth, physiology, and toxin content.

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Pseudo-nitzschia, Nitzschia, and domoic acid: New research since 2011

Cited by 289 publications

References 339 publications

Trophic interactions, toxicokinetics, and detoxification processes in a domoic acid‐producing diatom and two copepod species

Trophic interactions, toxicokinetics, and detoxification processes in a domoic acid‐producing diatom and two copepod species

Transcriptomic responses to grazing reveal the metabolic pathway leading to the biosynthesis of domoic acid and highlight different defense strategies in diatoms

Acclimation of the Marine Diatom Pseudo‐nitzschia australis to Different Salinity Conditions: Effects on Growth, Photosynthetic Activity, and Domoic Acid Content¹

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Pseudo-nitzschia, Nitzschia, and domoic acid: New research since 2011

Cited by 289 publications

References 339 publications

Trophic interactions, toxicokinetics, and detoxification processes in a domoic acid‐producing diatom and two copepod species

Trophic interactions, toxicokinetics, and detoxification processes in a domoic acid‐producing diatom and two copepod species

Transcriptomic responses to grazing reveal the metabolic pathway leading to the biosynthesis of domoic acid and highlight different defense strategies in diatoms

Acclimation of the Marine Diatom Pseudo‐nitzschia australis to Different Salinity Conditions: Effects on Growth, Photosynthetic Activity, and Domoic Acid Content1

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Acclimation of the Marine Diatom Pseudo‐nitzschia australis to Different Salinity Conditions: Effects on Growth, Photosynthetic Activity, and Domoic Acid Content¹