View source for Biology:Pseudo-nitzschia

{{Short description|Genus of marine planktonic diatoms}}
{{Automatic taxobox
| image = Pseudonitzschia2.jpg
| image_upright = 1.1
| taxon = Pseudo-nitzschia
| authority = H. Perag. in H. Perag. and Perag.
}}

'''''Pseudo-nitzschia''''' is a marine planktonic [[Biology:Diatom|diatom]] genus that accounts for 4.4% of pennate diatoms found worldwide.<ref>{{cite journal |last1= Malviya |first1= Shruti |last2= Scalco |first2= Eleonora |last3= Audic |first3= Stéphane |last4= Vincent |first4= Flora |last5= Alaguraj |first5= Veluchamy |last6= Poulain |first6= Julie |last7= Wincker |first7= Patrick |last8= Iudicone |first8= Daniele |last9= de Vargas |first9= Colomban |last10= Bittner |first10= Lucie |last11= Zingone |first11= Adriana |last12= Bowler |first12= Chris |title=Insights into global diatom distribution and diversity in the world's ocean|journal=Proc Natl Acad Sci U S A |date=15 March 2016 |volume=113 |issue=11 |pages=E1516-1525 |doi= 10.1073/pnas.1509523113 |pmid=26929361 |pmc= 4801293 |bibcode= 2016PNAS..113E1516M |doi-access= free }}</ref> Some species are capable of producing the [[Chemistry:Neurotoxin|neurotoxin]] [[Chemistry:Domoic acid|domoic acid]] (DA), which is responsible for the neurological disorder in humans known as [[Biology:Amnesic shellfish poisoning|amnesic shellfish poisoning]] (ASP). Currently,  58 species are known, 28 of which have been shown to produced DA. It was originally hypothesized that only dinoflagellates could produce harmful algal toxins, but a deadly bloom of ''Pseudo-nitzschia'' occurred in 1987 in the bays of Prince Edward Island, Canada, and led to an outbreak of ASP.<ref name="Maldonado et al 2002">{{cite journal |last1=Maldonado |first1=Maria T. |last2=Hughes |first2=Margaret P. |last3=Rue |first3=Eden L. |last4=Wells |first4=Mark L. |title=The effect of Fe and Cu on growth and domoic acid production by Pseudo-nitzschia multiseries and Pseudo-nitzschia australis |journal=Limnology and Oceanography |date=March 2002 |volume=47 |issue=2 |pages=515–526 |doi=10.4319/lo.2002.47.2.0515 |citeseerx=10.1.1.580.133 |bibcode=2002LimOc..47..515M |s2cid=85706962 }}</ref> Over 100 people were affected by this outbreak after consuming contaminated mussels; three people died.<ref name=pmid27011282>{{cite journal |last1=Lim |first1=Hong-Chang |last2=Leaw |first2=Chui-Pin |last3=Su |first3=Suriyanti Nyun-Pau |last4=Teng |first4=Sing-Tung |last5=Usup |first5=Gires |last6=Mohammad-Noor |first6=Normawaty |last7=Lundholm |first7=Nina |last8=Kotaki |first8=Yuichi |last9=Lim |first9=Po-Teen |title=Morphology and Molecular Characterization of ''Pseudo-Nitzschia'' (bacillariophyceae) from Malaysian Borneo, Including the New Species ''Pseudo-Nitzschia Circumpora'' Sp. Nov |journal=Journal of Phycology |date=October 2012 |volume=48 |issue=5 |pages=1232–1247 |doi=10.1111/j.1529-8817.2012.01213.x |pmid=27011282 |s2cid=29046420 }}</ref> Since this event, no additional deaths have been attributed to ASP, though the prevalence of toxic diatoms and DA has increased worldwide. This anomaly is likely due to increased awareness of harmful algal blooms (HABs) and their implications for human and ecosystem health.<ref name=pmid30420013/>

Blooms have since been characterized in coastal waters and the open-ocean worldwide and have been linked to increasing marine nutrient concentrations, warming ocean temperatures, and bacterial interactions.<ref name="Parsons & Dortch 2002">{{cite journal |last1=Parsons |first1=Michael L. |last2=Dortch |first2=Quay |title=Sedimentological evidence of an increase in Pseudo-nitzschia (Bacillariophyceae)abundance in response to coastal eutrophication |journal=Limnology and Oceanography |date=March 2002 |volume=47 |issue=2 |pages=551–558 |doi=10.4319/lo.2002.47.2.0551 |bibcode=2002LimOc..47..551P |s2cid=128974607 }}</ref><ref name=pmid30420013/>

== Morphology and physiology ==
[[File:Pseudo-nitzschia granii.png|thumb|upright=1.11| The diatom ''Pseudo-nitzschia granii'' is a common responder to iron enrichment in iron-limited regions of the ocean]]

''Pseudo-nitzschia'' species are bilaterally symmetrical pennate diatoms.  Cell walls are made up of elongated silica [[Biology:Frustule|frustule]]s. The silica wall is fairly dense which leads to negative buoyancy, providing a number of advantages. The wall allows the diatoms to sink to avoid light inhibition or nutrient limitations, as well as to protect against grazing zooplankton. The silica frustules also  contribute vastly to the sediment layers of the earth and to the fossil record, which makes them exceptionally useful in increasing understanding of numerous processes such as gauging the degree of climate change.<ref name=":4">{{cite book |doi=10.1007/978-4-431-55130-0_10 |chapter=Ecology and Evolution of Marine Diatoms and Parmales |title=Marine Protists |year=2015 |last1=Kuwata |first1=Akira |last2=Jewson |first2=David H. |pages=251–275 |isbn=978-4-431-55129-4 }}</ref> Before sinking to the ocean floor, every atom of silicon that enters the ocean is integrated into the cell wall of a diatom about 40 times.<ref name=":4" />

Silica frustules contain a central raphe, which secretes mucilage that allows the cells to move by gliding.<ref name="Lundholm & Moestrup 2002">{{cite journal |last1=Lundholm |first1=Nina |last2=Moestrup |first2=Øjvind |title=The marine diatom Pseudo-nitzschia galaxiae sp. nov. (Bacillariophyceae): morphology and phylogenetic relationships |journal=Phycologia |date=November 2002 |volume=41 |issue=6 |pages=594–605 |doi=10.2216/i0031-8884-41-6-594.1 |s2cid=84271624 }}</ref> Cells are often found in overlapped, stepped colonies, and exhibit collective motility.<ref name="Lundholm & Moestrup 2002"/> ''Pseudo-nitzschia'' species [[Biology:Autotroph|synthesize their own food]] through the use of light and nutrients in [[Earth:Photosynthesis|photosynthesis]]. The diatoms have a central [[Biology:Vacuole|vacuole]] to store nutrients for later use and a light-harvesting system to protect themselves against high-intensity light.<ref name=":4" />

== Taxonomy ==
The diatom lineage may go back 180 to 250 million years ago (Mya). About 65 Mya, diatoms survived a mass extinction in which roughly 85% of all species perished.<ref name=":4" /> Until 1994, the genus was known as ''[[Biology:Nitzschia|Nitzschia]]'', but was changed to ''Pseudo-nitzschia'' because of the ability to form chains of overlapping cells, as well as other minor morphological differences.<ref>{{cite journal|last1=Hasle|first1=Grethe Rytter|date=December 1994|title=''Pseudo-nitzschia'' as a genus distinct from ''Nitzschia'' (Bacillariophyceae)|journal=Journal of Phycology|volume=30|issue=6|pages=1036–1039|doi=10.1111/j.0022-3646.1994.01036.x|s2cid=84397672|doi-access=free}}</ref> While the genus can be readily recognized using [[Engineering:Optical microscope|light microscopy]], identification of distinct species can require taxonomic expertise and be extremely time-consuming. Species identification in this genus is notoriously difficult due to the presence of cryptic species. Similar species are often differentiated by very small differences in the frustule, such as shape, period, and band stria.<ref name=pmid27011282/>

The direct impacts of species identification on public health make this a serious concern. Toxogenic and nontoxogenic species commonly co-occur; therefore, discrimination between various ''Pseudo-nitzschia'' species is imperative to determine the potential toxicity of an algal bloom. Optical microscopy identification techniques are inadequate when a large number of samples must be routinely examined, such as is required for a monitoring program for public health. Recently, a [[Biology:DNA microarray|DNA-microarray]] was developed for simultaneous detection of multiple harmful algal bloom species with an emphasis on ''Pseudo-nitzschia''. The total assay is believed to have the potential to identify hundreds of species and accurately differentiate between large quantities of related species. Additionally, this technology has been shown to accurately identify toxic [[Earth:Phytoplankton|phytoplankton]] even at extremely low concentrations. The lower limit for detection of ''Pseudo-nitzschia'' is as low as 500 cells.<ref>{{cite journal |last1=Noyer |first1=Charlotte |last2=Abot |first2=Anne |last3=Trouilh |first3=Lidwine |last4=Leberre |first4=Véronique Anton |last5=Dreanno |first5=Catherine |title=Phytochip: Development of a DNA-microarray for rapid and accurate identification of Pseudo-nitzschia spp and other harmful algal species |journal=Journal of Microbiological Methods |date=May 2015 |volume=112 |pages=55–66 |doi=10.1016/j.mimet.2015.03.002 |pmid=25765159 |url=https://archimer.ifremer.fr/doc/00254/36554/ }}</ref>

The nomenclatural history is given in Hasle (1995)<ref>{{cite journal|last1=Hasle|first1=Grethe Rytter|date=June 1995|title=''Pseudo-nitzschia pungens'' and ''P. multiseries'' (Bacillariophyceae): nomenclatural history, morphology, and distribution|journal=Journal of Phycology|volume=31|issue=3|pages=428–435|doi=10.1111/j.0022-3646.1995.00428.x|s2cid=85353205}}</ref> and Bates (2000).<ref>{{cite journal |last1=Bates |first1=Stephen S. |title=Domoic-acid-producing diatoms: another genus added! |journal=Journal of Phycology |date=7 July 2008 |volume=36 |issue=6 |pages=978–983 |doi=10.1046/j.1529-8817.2000.03661.x |s2cid=85883095 |doi-access=free }}</ref>

== Lifecycle ==

=== Ornithine-urea cycle ===
The physiological distribution, fixation, and recycling center for inorganic carbon and nitrogen plays a key role in the metabolic response of diatoms to prolonged nutrient deprivation. The cycle enables diatoms to respond immediately to the availability of nutrients and recover by increasing their metabolic and growth rates.<ref name=":4" />

=== Resting stages ===
Diatoms have the ability to enter two distinct resting stages to overcome periods of stress. A resting spore has a great capacity to survive over extended periods of nutrient deprivation. To avoid low nutrient concentrations during stratification, the resting spores can settle to the bottom where the nutrient concentration is higher. A resting cell is better able to rapidly respond when nutrients become available again. This is more often observed in freshwater and pennate diatoms like ''Pseudo-nitzschia''.<ref name=":4" /> There is contradictory evidence regarding the presence or absence of a resting stage in ''Pseudo-nitzschia''.<ref name="Lelong et al 2012">{{cite journal |last1=Lelong |first1=Aurélie |last2=Hégaret |first2=Hélène |last3=Soudant |first3=Philippe |last4=Bates |first4=Stephen S. |title=Pseudo-nitzschia (Bacillariophyceae) species, domoic acid and amnesic shellfish poisoning: revisiting previous paradigms |journal=Phycologia |date=March 2012 |volume=51 |issue=2 |pages=168–216 |doi=10.2216/11-37.1 |s2cid=55094773 }}</ref>

=== Reproduction ===
Among diatoms, reproduction is primarily asexual by [[Biology:Fission|binary fission]], with each daughter cell receiving one of the parent’s cell’s two frustules. However, this asexual division results in a size reduction. To restore the cell size of a diatom population, sexual reproduction must occur. Vegetative diploid cells undergo meiosis to produce active and passive gametes. These gametes then fuse to form a zygote, which then develops into an auxospore.<ref name=pmid26494151>{{cite journal |last1=Scalco |first1=Eleonora |last2=Amato |first2=Alberto |last3=Ferrante |first3=Maria Immacolata |last4=Montresor |first4=Marina |title=The sexual phase of the diatom Pseudo-nitzschia multistriata: cytological and time-lapse cinematography characterization |journal=Protoplasma |date=November 2016 |volume=253 |issue=6 |pages=1421–1431 |doi=10.1007/s00709-015-0891-5 |pmid=26494151 |s2cid=8440667 }}</ref> Sexual reproduction leads to both an increase in genotypic diversity and the formation of large initial cells through formation of  the auxospore. Cells need to be below a species-specific size threshold for the sexual phase to be induced. Many external cues also regulate the initiation, such as day length, irradiance, and temperature.<ref name=pmid26988637>{{cite journal |last1=Scalco |first1=Eleonora |last2=Stec |first2=Krzysztof |last3=Iudicone |first3=Daniele |last4=Ferrante |first4=Maria Immacolata |last5=Montresor |first5=Marina |title=The dynamics of sexual phase in the marine diatom Pseudo-nitzschia multistriata (Bacillariophyceae) |journal=Journal of Phycology |date=October 2014 |volume=50 |issue=5 |pages=817–828 |doi=10.1111/jpy.12225 |pmid=26988637 |s2cid=22196101 |doi-access=free }}</ref>

The basic mode of the sexual phase of reproduction appears to be conserved among ''Pseudo-nitzschia'' species. Upon mixing two strains of compatible mating type and of appropriate cell size for sexualization, cells  align side by side and differentiate into gametangia. One active (+) and one passive (-) gamete are then produced within each gametangium. The active gamete migrates toward the passive partner and [[Biology:Bacterial conjugation|conjugate<nowiki/>s]]. The zygote is then becomes an auxospore, which has no rigid frustule. Inside the auxospore, a large initial cell is produced.<ref name=pmid26494151/>

Sexual reproduction appears to occur exclusively in the exponential growth phase and be linked to cell density. Sexualization can only be initiated when a species-specific threshold cell concentration is met. Decreasing the distance to facilitate contact and/or perception of chemical cues between cells triggers the sexual phase, indicating that high cell density is favorable for sexual reproduction. Additionally, the onset of sexualization is linked to a significant reduction in growth of the vegetative and parental cells, suggesting that vegetative division is inhibited when the two strains of opposite mating type come in contact.<ref name=pmid26988637/>

== Genome and transcriptome ==

''Pseudo-nitzschia multiseries'' has a genome consisting of 219 megabases (Mb) and a full genome project is underway.<ref>{{Cite web|url=http://genome.jgi.doe.gov/Psemu1/Psemu1.info.html|title=Info - Pseudo-nitzschia multiseries CLN-47|website=genome.jgi.doe.gov|access-date=2016-05-06}}</ref>

Transcriptomes of three species, ''P. arenysensis, P. delicatissima'', and ''P. multistriata'', have been sequenced. The transcriptomes encode between 17,500 and 20,200 proteins. ''P. multistriata'' was found to uniquely encode [[Biology:Nitric oxide synthase|nitric oxide synthase]].<ref>{{cite journal |last1=Di Dato |first1=Valeria |last2=Musacchia |first2=Francesco |last3=Petrosino |first3=Giuseppe |last4=Patil |first4=Shrikant |last5=Montresor |first5=Marina |last6=Sanges |first6=Remo |last7=Ferrante |first7=Maria Immacolata |title=Transcriptome sequencing of three Pseudo-nitzschia species reveals comparable gene sets and the presence of Nitric Oxide Synthase genes in diatoms |journal=Scientific Reports |date=20 July 2015 |volume=5 |page=12329 |doi=10.1038/srep12329 |pmid=26189990 |pmc=4648414 |bibcode=2015NatSR...512329D }}</ref>

Recently, transcriptome analysis of ''P. multiseries'' was used to identify a four-gene cluster linked to DA biosynthesis.<ref>{{cite journal |last1=Brunson|first1=John K. |last2=McKinnie|first2=Shaun M.K.|last3=Chekan|first3=Johnathan R.|last4=McCrow|first4=John P.|last5=Miles|first5=Zachary D.|last6=Bertrand|first6=Erin M.|last7=Bielinski|first7=Vincent A.|last8=Luhavaya|first8=Hannah|last9=Obornic|first9=Miroslav|last10=Smith|first10=G. Jason|last11=Hutchins|first11=David A.|last12=Allen|first12=Andrew E.|last13=Moore|first13=Bradley S. |title=Biosynthesis of the neurotoxin domoic acid in a bloom-forming diatom |journal=Science |date=28 September 2018 |volume=361 |issue=6409 |pages=1356–1358 |doi=10.1126/science.aau0382 |pmid=30262498 |pmc=6276376 |bibcode=2018Sci...361.1356B |doi-access=free}}</ref> The identification of these genes presents an opportunity to monitor toxic blooms of ''Pseudo-nitzschia'' genetically in order to better understand the toxicity and environmental conditions that cause them.

== Habitat ==
In general, diatoms flourish in nutrient-rich waters with high light penetration.<ref name=":4" /> Some species of ''Pseudo-nitzschia'' can grow in a broad temperature range ({{convert|4|-|20|C|F|disp=or}}), making it possible for them to inhabit a diverse range of habitats.<ref name="An unprecedented coastwide toxic al">{{cite journal |last1=McCabe |first1=R.M. |last2=Hickey |first2=B.M. |last3=Kudela |first3=R.M. |last4=Lefebvre |first4=K.A. |last5=Adams |first5=N.G. |title= An unprecedented coastwide toxic algal bloom linked to anomalous ocean conditions |journal=Geophysical Research Letters |date=September 2016 |volume=43 |issue=19 |pages=10366–10376 |doi= 10.1002/2016GL070023|pmid=27917011 |pmc=5129552 |bibcode=2016GeoRL..4310366M |doi-access=free }}</ref>

''Pseudo-nitzschia'' species have been observed in all oceans of the world, including the Arctic and Antarctic.<ref name=pmid30420013/>  In North America, they have been documented along the Pacific coast from Canada to California, along the Atlantic Northeast coast of Canada, North Carolina, and the Gulf of Mexico.<ref>{{Cite web|url=http://products.coastalscience.noaa.gov/pmn/_docs/Factsheets/Factsheet_Pseudonitzschia.pdf|title=NOAA Coastal Science|last=|first=|date=|website=|publisher=|access-date=}}</ref> Various species have been detected in the open ocean as well as gulfs and bays, showing a presence in many diverse environments, including off the coasts of Canada, Portugal, France, Italy, Croatia, Greece, Ireland, Australia, Morocco, Japan, Spain, Tunisia, Namibia, Singapore, Angola, Philippines, Turkey, Ukraine, Argentina, and Uruguay.<ref name=pmid25955528>{{cite journal |last1=Dhar |first1=Bidhan |last2=Cimarelli |first2=Lucia |last3=Singh |first3=Kumar |last4=Brandi |first4=Letizia |last5=Brandi |first5=Anna |last6=Puccinelli |first6=Camilla |last7=Marcheggiani |first7=Stefania |last8=Spurio |first8=Roberto |title=Molecular Detection of a Potentially Toxic Diatom Species |journal=International Journal of Environmental Research and Public Health |date=6 May 2015 |volume=12 |issue=5 |pages=4921–4941 |doi=10.3390/ijerph120504921 |pmid=25955528 |pmc=4454946 |doi-access=free }}</ref><ref name=pmid30420013/>

Given the warming temperatures of ocean water, decreasing sea ice, and increasing light penetration brought on by climate change, it is likely that the season for favorable growth of toxigenic ''Pseudo-nitzschia'' species will expand.<ref name=pmid30420013/> It is important to continue monitoring ''Pseudo-nitzschia'' blooms and their toxicity, particularly in Arctic and Antarctic habitats that may begin to see higher prevalence of these species.

== Harmful bloom dynamics ==
Harmful algal blooms (HABs) of Pseudo-nitzschia and the like can cause diseases and death in many marine organisms, as well as the humans who consume them. HABs can result in oxygen depletion caused by increased biomass production. However, blooms of ''Pseudo-nitzschia'' more commonly cause harm through the production of the toxin DA, which can be transferred to other trophic levels through bioaccumulation.

DA can often be detected in shellfish flesh during and immediately following a toxic bloom.<!--<ref doi.org/10.1080/03067318908026867/> --> Though shellfish harvest closures are typically based on cells counts of ''Pseudo-nitzschia'' present, these cell counts do not always correlate with DA levels.<ref name=pmid30420013/>  Thus, it is important to understand the other environmental drivers that may lead to higher production of DA.

The largest recorded DA event caused by ''Pseudo-nitzschia'' took place along the North American west coast in 2015, causing prolonged closures of razor clam, rock crab, and Dungeness crab fisheries. Later in 2015, DA was detected in whales, dolphins, porpoises, seals, and sea lions. This bloom was dominated by P. australis and likely caused by anomalous warm water and nutrients brought to the surface by upwelling conditions.<ref name="An unprecedented coastwide toxic al"/>

Prior to this 2015 bloom, the largest ''Pseudo-nitzschia'' bloom recorded occurred in September 2004 off the northwest coast of the United States. The maximum cell densities during this bloom reached 13 x 10<sup>6</sup> cells per liter, with domoic acid levels of 1.3 pg DA/cell.<ref name=pmid27008397>{{cite journal |last1=Auro |first1=Maureen E. |last2=Cochlan |first2=William P. |title=Nitrogen Utilization and Toxin Production by Two Diatoms of the Pseudo-nitzschia pseudodelicatissima Complex: P. cuspidata and P. fryxelliana |journal=Journal of Phycology |date=February 2013 |volume=49 |issue=1 |pages=156–169 |doi=10.1111/jpy.12033 |pmid=27008397 |s2cid=19106015 }}</ref>

Sediment cores indicate a link between increasing coastal nutrient levels ([[Earth:Eutrophication|eutrophication]]) and an increase in ''Pseudo-nitzschia'' blooms.<ref name="Parsons & Dortch 2002"/>

[[File:NOAA July 2015 Average Chlorophyll Concentrations (milligrams per cubic meter of water).jpg|thumb|The largest toxic Pseudo-nitzschia bloom was recorded in 2015 along the west coast of North America.]]

== Domoic acid ==
[[File:Pseudo-nitzschia.jpg|thumb|''Pseudo-nitzchia'']]
Shellfish become contaminated after feeding on toxic ''Pseudo-nitzschia'' blooms and can act as a vector to transfer domoic acid to humans upon ingestion. DA acts as a potent glutamate agonist and is responsible for amnesic shellfish poisoning in humans. Effects can be as minor as vomiting, cramps, and a headache, or as severe as permanent anterograde memory loss, coma, and death.<ref>Teitelbaum, J. S., Zatorre, R. J., Carpenter, S., Gendron, D., Evans, A. C., Gjedde, A., & Cashman, N. R. (1990). Neurologic sequelae of domoic acid intoxication due to the ingestion of contaminated mussels. New England Journal of Medicine, 322(25), 1781-1787. [https://www.nejm.org/doi/full/10.1056/NEJM199006213222505 doi: 10.1056/NEJM199006213222505]</ref> So, monitoring systems and management practices for recreational and commercial fishing are important to ensure the health of marine animals and their predators.

Photosynthesis is essential for the production of domoic acid. Periods of darkness or chemical inhibition of photosynthesis has been shown to inhibit toxin production. Additionally, DA production peaks in the stationary phase of the growth cycle when cell division is slowed or absent. Production is minimal or nonexistent during the exponential phase, and ceases completely during the death phase of the growth cycle.<ref name=pmid27008397/>

=== Factors affecting production ===
Many factors have been linked to promotion of DA production, including sufficient light, elevated or decreased pH, and nutrition limitations.<ref name="Lelong et al 2012"/><ref name=pmid30420013>{{cite journal |last1=Bates |first1=Stephen S. |last2=Hubbard |first2=Katherine A. |last3=Lundholm |first3=Nina |last4=Montresor |first4=Marina |last5=Leaw |first5=Chui Pin |title=Pseudo-nitzschia, Nitzschia, and domoic acid: New research since 2011 |journal=Harmful Algae |date=November 2018 |volume=79 |pages=3–43 |doi=10.1016/j.hal.2018.06.001 |pmid=30420013 |s2cid=53292428 |doi-access=free }}</ref> In one species, ''P. cuspidata'', a link has been indicated between toxicity and photosynthesis photon flux density (PPFD). At a low PPFD, the exponential growth rate approximately halved and the cells were significantly more toxic.<ref name=pmid27008397/>

While the effect of availability of different nitrogen sources on toxicity has been studied many times, no general rule could be demonstrated for differences in growth and DA production, with the results varying greatly by species. However, toxin production increases when the nitrogen source could not sustain a high biomass, suggesting growth limitation seems to induce toxicity.<ref>{{cite journal |last1=Martin-Jézéquel |first1=Véronique |last2=Calu |first2=Guillaume |last3=Candela |first3=Leo |last4=Amzil |first4=Zouher |last5=Jauffrais |first5=Thierry |last6=Séchet |first6=Véronique |last7=Weigel |first7=Pierre |title=Effects of Organic and Inorganic Nitrogen on the Growth and Production of Domoic Acid by Pseudo-nitzschia multiseries and P. australis (Bacillariophyceae) in Culture |journal=Marine Drugs |date=26 November 2015 |volume=13 |issue=12 |pages=7067–7086 |doi=10.3390/md13127055 |pmid=26703627 |pmc=4699229 |doi-access=free }}</ref>

The presence of [[Earth:Zooplankton|zooplankton]] has also been shown to affect the toxicity of ''Pseudo-nitzschia''. The presence of [[Biology:Copepod|copepod]]s was shown to enhance toxin production of ''P. seriata''. This effect appears to be chemically mediated, as it could be induced without physical contact.<ref>{{cite journal |last1=Tammilehto |first1=Anna |last2=Nielsen |first2=Torkel Gissel |last3=Krock |first3=Bernd |last4=Møller |first4=Eva Friis |last5=Lundholm |first5=Nina |title=Induction of domoic acid production in the toxic diatom Pseudo-nitzschia seriata by calanoid copepods |journal=Aquatic Toxicology |date=February 2015 |volume=159 |pages=52–61 |doi=10.1016/j.aquatox.2014.11.026 |pmid=25521565 |url=https://epic.awi.de/id/eprint/36908/1/Tammilehto_2015.pdf }}</ref>

''Pseudo-nitzschia'' species also appear to respond dramatically to differences in trace metal concentrations, such as iron (Fe) and copper (Cu). In Fe-limited conditions, ''Pseudo-nitzschia'' increases DA production by six to 25 times as a result of stress.<ref name="Maldonado et al 2002"/> This increase allows them to enhance Fe acquisition needed for metabolic activities, and can have devastating effects.

== Known species ==
Over fifty species<!--54 including uncertain, unassessed species--> of ''Pseudo-nitzschia'' have been described (following WoRMS<ref>{{BioRef|WoRMS |title=''Pseudo-nitzschia'' |db=DiatomBase |year=2019 |id=149151 |access-date=10 September 2019}}</ref> unless specified):
{{col-float-break}}
*''Pseudo-nitzschia abrensis'' {{small| Pérez-Aicua & Orive, 2013}}
*''Pseudo-nitzschia allochrona'' {{small| Zingone, Percopo et Sarno, 2022}}<ref>{{cite journal | url=https://doi.org/10.1002/ece3.9155 | doi=10.1002/ece3.9155 | title=Phenological segregation suggests speciation by time in the planktonic diatom Pseudo‐''Nitzschia allochrona'' sp. nov. | year=2022 | last1=Percopo | first1=Isabella | last2=Ruggiero | first2=Maria Valeria | last3=Sarno | first3=Diana | last4=Longobardi | first4=Lorenzo | last5=Rossi | first5=Rachele | last6=Piredda | first6=Roberta | last7=Zingone | first7=Adriana | journal=Ecology and Evolution | volume=12 | issue=8 | pages=e9155 | pmid=35949533 | pmc=9352866 }}</ref>
*''Pseudo-nitzschia americana'' {{small| (Hasle) Fryxell, 1993}}<ref name = "Lundholm">{{Cite journal|last1=Lundholm|first1=Nina|last2=Hasle|first2=Grethe Rytter|last3=Fryxell|first3=Greta A.|author-link3=Greta Fryxell|last4=Hargraves|first4=Paul E.|date=2002-09-01|title=Morphology, phylogeny and taxonomy of species within the Pseudo-nitzschia americana complex (Bacillariophyceae) with descriptions of two new species, Pseudo-nitzschia brasiliana and Pseudo-nitzschia linea|url=https://doi.org/10.2216/i0031-8884-41-5-480.1|journal=Phycologia|volume=41|issue=5|pages=480–497|doi=10.2216/i0031-8884-41-5-480.1|s2cid=85308820|issn=0031-8884}}</ref>
*''Pseudo-nitzschia antarctica'' (uncertain, unassessed)<ref>{{BioRef|WoRMS |title=''Pseudonitzschia antarctica'' |db=DiatomBase |year=2019 |id=341572 |access-date=10 September 2019}}</ref>
*''Pseudo-nitzschia arctica'' {{small| Percopo & Sarno, 2016}}
*''Pseudo-nitzschia arenysensis'' {{small| Quijano-Scheggia, Garcés & Lundholm, 2009}}
*''[[Biology:Pseudo-nitzschia australis|Pseudo-nitzschia australis]]'' {{small| Frenguelli, 1939}}
*''Pseudo-nitzschia batesiana'' {{small| H.C.Lim, S.T.Teng, C.P.Leaw & P.T.Lim, 2013}}
*''Pseudo-nitzschia bipertita'' {{small| S.T.Teng, H.C.Lim & C.P.Leaw, 2016}}
*''Pseudo-nitzschia brasiliana'' {{small| N.Lundholm, G.R.Hasle & G.A.Fryxell, 2002}}<ref name = "Lundholm"/>
*''Pseudo-nitzschia bucculenta'' {{small| F. Gai, C. K. Hedemand, N. Lundholm & Ø. Moestrup, 2018}} <ref>{{cite journal |last1=Gai |first1=Frederik Frøsig |last2=Hedemand |first2=Cecilie Kirketerp |last3=Louw |first3=Deon C. |last4=Grobler |first4=Kolette |last5=Krock |first5=Bernd |last6=Moestrup |first6=Øjvind |last7=Lundholm |first7=Nina |title=Morphological, molecular and toxigenic characteristics of Namibian Pseudo-nitzschia species – including Pseudo-nitzschia bucculenta sp. nov. |journal=Harmful Algae |date=1 June 2018 |volume=76 |pages=80–95 |doi=10.1016/j.hal.2018.05.003 |pmid=29887207 |s2cid=47004943 |url=https://epic.awi.de/id/eprint/47348/1/Gai_2018.pdf }}</ref>
*''Pseudo-nitzschia caciantha'' {{small| Lundholm, Moestrup & Hasle, 2003}}
*''Pseudo-nitzschia calliantha'' {{small| Lundholm, Moestrup & Hasle, 2003}}
*''Pseudo-nitzschia chiniana'' {{small| C.X. Huang & Yang Li, 2019}}<ref name="Species composition and toxicity of">{{cite journal |last1=Huang |first1=Chun Xiu |last2=Dong |first2=Huan Chang |last3=Lundholm |first3=Nina |last4=Teng |first4=Sing Tung |last5=Zheng |first5=Guan Chao |last6=Tan |first6=Zhi Jun |last7=Lim |first7=Po Teen |last8=Li |first8=Yang |title=Species composition and toxicity of the genus Pseudo-nitzschia in Taiwan Strait, including P. chiniana sp. nov. and P. qiana sp. nov. |journal=Harmful Algae |date=1 April 2019 |volume=84 |pages=195–209 |doi=10.1016/j.hal.2019.04.003 |pmid=31128805 |s2cid=145898027 }}</ref>
*''Pseudo-nitzschia circumpora'' {{small| H.C.Lim, C.P.Leaw & P.T.Lim, 2012}}
*''Pseudo-nitzschia cuspidata'' {{small| (Hasle) Hasle, 1993}}
*''Pseudo-nitzschia decipiens'' {{small| Lundholm & Moestrup, 2006}} (uncertain, unassessed)
*''Pseudo-nitzschia delicatissima'' {{small| (Cleve) Heiden, 1928}}
*''Pseudo-nitzschia dolorosa'' {{small| Lundholm & Moestrup, 2006}} (uncertain, unassessed)
*''Pseudo-nitzschia fraudulenta'' {{small| (Cleve) Hasle, 1993}}
*''Pseudo-nitzschia fryxelliana'' {{small| Lundholm, 2012}}
*''Pseudo-nitzschia fukuyoi'' {{small| H.Ch.Lim, S.T.Teng, Ch.P.Leaw & P.T.Lim, 2013}}
*''Pseudo-nitzschia galaxiae'' {{small| N.Lundholm & Ø.Moestrup, 2002}}
*''Pseudo-nitzschia granii'' {{small| (G.R.Hasle) G.R.Hasle, 1974}}
*''Pseudo-nitzschia hainanensis'' {{small| X.M. Chen & Y. Li, 2020}} <ref>{{cite journal|author1=Chen, X.M.|author2= J. Pang|author3= C.X. Huang|author4= N. Lundholm|author5= S.T. Teng|author6= A. Li|author7= Y. Li|year= 2020|title= Two new and non-toxigenic Pseudo-nitzschia species (Bacillariophyceae) from Chinese southeast coastal waters|journal= J. Phycol.|volume= 57|issue= 1|pages= 335–344|doi=10.1111/jpy.13101 |pmid= 33174223|doi-access= free}}</ref>
*''Pseudo-nitzschia hallegraeffii'' {{small| P.A. Ajani, A. Verma et S.A. Murray, 2018}} <ref>{{cite journal |last1=Ajani |first1=Penelope A. |last2=Verma |first2=Arjun |last3=Lassudrie |first3=Malwenn |last4=Doblin |first4=Martina A. |last5=Murray |first5=Shauna A. |last6=Vazquez-Duhalt |first6=Rafael |title=A new diatom species P. hallegraeffii sp. nov. belonging to the toxic genus Pseudo-nitzschia (Bacillariophyceae) from the East Australian Current |journal=PLOS ONE |date=12 April 2018 |volume=13 |issue=4 |pages=e0195622 |doi=10.1371/journal.pone.0195622 |pmid=29649303 |pmc=5896966 |url=https://opus.lib.uts.edu.au/bitstream/10453/127354/1/A%20new%20diatom%20species%20P.%20hallegraeffii%20sp.%20nov.%20belonging%20to%20the%20toxic%20genus%20Pseudo-nitzschia%20%28Bacillariophyceae%29%20from%20the%20East%20Australian%20Current.pdf |bibcode=2018PLoSO..1395622A |doi-access=free }}</ref>
*''Pseudo-nitzschia hasleana'' {{small| Lundholm, 2012}}
*''Pseudo-nitzschia heimii'' {{small| Manguin, 1957}}
*''Pseudo-nitzschia inflatula'' {{small| (G.R.Hasle) G.R.Hasle, 1993}}
*''Pseudo-nitzschia kodamae'' {{small| S.T. Teng, H.C. Lim, C.P. Leaw & P.T. Lim, 2015}}
{{col-float-break}}
*''Pseudo-nitzschia limii'' {{small| S.T.Teng, H.C.Lim & C.P.Leaw, 2016}}
*''Pseudo-nitzschia linea'' {{small| Lundholm, Hasle & G.A.Fryxell, 2002}}<ref name = "Lundholm"/>
*''Pseudo-nitzschia lineola'' {{small| (Cleve) Hasle, 1965}}
*''Pseudo-nitzschia lundholmiae'' {{small| H.C.Lim, S.T.Teng, C.P.Leaw & P.T.Lim, 2013}}
*''Pseudo-nitzschia mannii'' {{small| Amato & Montresor, 2008}} (uncertain, unassessed)
*''Pseudo-nitzschia micropora'' {{small| K.Priisholm, Ø.Moestrup & N.Lundholm, 2002}} (uncertain, unassessed)
*''Pseudo-nitzschia multiseries'' {{small| (Hasle) Hasle, 1995}}
*''Pseudo-nitzschia multistriata'' {{small| (Takano) Takano, 1995}}
*''Pseudo-nitzschia nanaoensis'' {{small| Yang Li & H.C. Dong, 2018}} <ref>{{cite journal |last1=Li |first1=Yang |last2=Dong |first2=Huan Chang |last3=Teng |first3=Sing Tung |last4=Bates |first4=Stephen S. |last5=Lim |first5=Po Teen |last6=Kroth |first6=P. |title=''Pseudo‐nitzschia nanaoensis'' sp. nov. (Bacillariophyceae) from the Chinese coast of the South China Sea |journal=Journal of Phycology |date=December 2018 |volume=54 |issue=6 |pages=918–922 |doi=10.1111/jpy.12791 |pmid=30270437 |s2cid=52892283 |url=http://ir.unimas.my/id/eprint/25895/1/Pseudo-nitzschia%20nanaoensis%20sp.%20nov.%20%28Bacillariophyceae%29%20from%20the%20Chinese%20coast%20of%20the%20South%20China%20Sea%20%28abstract%29.pdf }}</ref>
*''Pseudo-nitzschia obtusa'' {{small| (Hasle) Hasle & Lundholm, 2005}}
*''Pseudo-nitzschia plurisecta'' {{small| Orive & Pérez-Aicua, 2013}}
*''Pseudo-nitzschia prolongatoides'' {{small| (G.R.Hasle) G.R.Hasle, 1993}}
*''Pseudo-nitzschia pseudodelicatissima'' {{small| (Hasle) Hasle, 1993}}
*''Pseudo-nitzschia pungens'' {{small| (Grunow ex Cleve) G.R.Hasle, 1993}}
*''Pseudo-nitzschia pungiformis'' {{small| (G.R.Hasle) G.R.Hasle, 1993}}
*''Pseudo-nitzschia qiana'' {{small| C.X. Huang & Yang Li, 2019}}<ref name="Species composition and toxicity of"/>
*''Pseudo-nitzschia roundii'' {{small| D.U.Hernández-Becerril, 2006}}
*''Pseudo-nitzschia sabit'' {{small| S.T. Teng, H.C. Lim, P.T. Lim & C.P. Leaw, 2015}}
*''Pseudo-nitzschia seriata'' {{small| (Cleve) H.Peragallo, 1899}}
*''Pseudo-nitzschia simulans'' {{small| Li, Huang & Xu, 2017}}
*''Pseudo-nitzschia sinica'' {{small| Y.Z.Qi & J.Wang, nom. inval.}} <ref>{{Cite web|url=https://www.algaebase.org/search/species/detail/?species_id=148192|title=Pseudo-nitzschia sinica Y.Z.Qi & J.Wang, nom. Inval. 1994 :: Algaebase}}</ref>
*''Pseudo-nitzschia subcurvata'' {{small| (G.R.Hasle) G.A.Fryxell, 1993}}
*''Pseudo-nitzschia subfraudulenta'' {{small| (G.R.Hasle) G.R.Hasle, 1993}}
*''Pseudo-nitzschia subpacifica'' {{small| (Hasle) Hasle, 1993}}
*''Pseudo-nitzschia taiwanensis'' {{small| X.M. Chen & Y. Li, 2020}} <ref>Chen, X.M., J. Pang, C.X. Huang, N. Lundholm, S.T. Teng, A. Li, and Y. Li. 2020. Two new and non-toxigenic Pseudo-nitzschia species (Bacillariophyceae) from Chinese southeast coastal waters. J. Phycol. doi.org/10.1111/jpy.13101 https://onlinelibrary.wiley.com/doi/10.1111/jpy.13101</ref>
*''Pseudo-nitzschia turgidula'' {{small| (Hustedt) G.R.Hasle, 1993}}
*''Pseudo-nitzschia turgiduloides'' {{small| (G.R.Hasle) G.R.Hasle, 1996}} (uncertain, unassessed)
*''Pseudo-nitzschia uniseriata'' {{small| H.C. Dong & Y. Li, 2020}}<ref name="Dong et al 2020">{{cite journal |last1=Dong |first1=Huan Chang |last2=Lundholm |first2=Nina |last3=Teng |first3=Sing Tung |last4=Li |first4=Aifeng |last5=Wang |first5=Chao |last6=Hu |first6=Yang |last7=Li |first7=Yang |title=Occurrence of Pseudo-nitzschia species and associated domoic acid production along the Guangdong coast, South China Sea |journal=Harmful Algae |date=1 September 2020 |volume=98 |pages=101899 |doi=10.1016/j.hal.2020.101899 |pmid=33129456 |s2cid=225338071 }}</ref>
*''Pseudo-nitzschia yuensis'' {{small| H.C. Dong & Y. Li, 2020}}<ref name="Dong et al 2020"/>

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Many species of ''Pseudo-nitzschia'' have been shown to produce domoic acid, although not all strains are toxigenic.<ref name="Lelong et al 2012"/><ref name=pmid30420013/><ref>{{cite web|title=HABS taxon details: ''Pseudo-nitzschia''|website=Taxonomic Reference List of Harmful Micro Algae |access-date=10 September 2019 |url=http://www.marinespecies.org/HAB/aphia.php?p=taxdetails&id=149151 |via=[[Organization:World Register of Marine Species|World Register of Marine Species]]}}</ref>

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*''Pseudo-nitzschia abrensis''
*''Pseudo-nitzschia australis''
*''Pseudo-nitzschia batesiana''
*''Pseudo-nitzschia bipertita''<ref name="Dong et al 2020"/>
*''Pseudo-nitzschia brasiliana''
*''Pseudo-nitzschia caciantha''
*''Pseudo-nitzschia calliantha''
*''Pseudo-nitzschia cuspidata''
*''Pseudo-nitzschia delicatissima''
*''Pseudo-nitzschia fraudulenta''
*''Pseudo-nitzschia fukuyoi''
*''Pseudo-nitzschia galaxiae''
*''Pseudo-nitzschia granii''
*''Pseudo-nitzschia hasleana''
*''Pseudo-nitzschia kodamae''
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*''Pseudo-nitzschia lundholmiae''
*''Pseudo-nitzschia multiseries''
*''Pseudo-nitzschia multistriata''
*''Pseudo-nitzschia obtusa''
*''Pseudo-nitzschia plurisecta''
*''Pseudo-nitzschia pseudodelicatissima''
*''Pseudo-nitzschia pungens''
*''Pseudo-nitzschia seriata''
*''Pseudo-nitzschia simulans''
*''Pseudo-nitzschia subcurvata''<ref>Olesen, A.J., A. Leithoff, A. Altenburger, B. Krock, B. Beszteri, S.L. Eggers, and N. Lundholm. 2021. First evidence of the toxin domoic acid in Antarctic diatom species. Toxins 13: 93. DOI:10.3390/toxins13020093</ref>
*''Pseudo-nitzschia subfraudulenta''
*''Pseudo-nitzschia subpacifica''
*''Pseudo-nitzschia turgidula''
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== References ==
{{Reflist}}

<!-- == Further reading ==
The general biology, physiology, toxicity and distribution of ''Pseudo-nitzschia'' species is reviewed in Bates and Trainer (2006),<ref>{{cite journal |doi=10.1007/978-3-540-32210-8_7 }}</ref> Trainer et al. (2008),<ref>{{cite book |last1=Trainer |first1=V.L. |first2=B.M. |last2=Hickey |first3=S.S. |last3=Bates |year=2008 |chapter=Toxic diatoms |chapter-url=https://books.google.com/books?id=LMZPqW-PmFYC&pg=PA219 |editor1-first=P.J. |editor1-last=Walsh |editor2-first=S.L. |editor2-last=Smith |editor3-first=L.E. |editor3-last=Fleming |editor4-first=H. |editor4-last=Solo-Gabriele |editor5-first=W.H. |editor5-last=Gerwick |title=Oceans and human health: risks and remedies from the sea |publisher=Elsevier Science Publishers |location=New York |pages=219-237 }}</ref> Lelong et al. (2012)<ref name="Lelong et al 2012"/> and Trainer et al. (2012).<ref>{{cite journal |last1=Trainer |first1=Vera L. |last2=Bates |first2=Stephen S. |last3=Lundholm |first3=Nina |last4=Thessen |first4=Anne E. |last5=Cochlan |first5=William P. |last6=Adams |first6=Nicolaus G. |last7=Trick |first7=Charles G. |title=Pseudo-nitzschia physiological ecology, phylogeny, toxicity, monitoring and impacts on ecosystem health |journal=Harmful Algae |date=1 February 2012 |volume=14 |pages=271–300 |doi=10.1016/j.hal.2011.10.025 }}</ref>

 -->

== External links ==
* Light and [[Engineering:Electron microscope|electron microscope]] images of ''Pseudo-nitzschia'' species are shown at the [http://nordicmicroalgae.org/taxon/Pseudo-nitzschia Nordic Microalgae website].
* Scanning electron microscopy images at the [http://www.mta.ca/dmf/images.html Digital Microscopy Facility website].
*[https://inter-j01.dfo-mpo.gc.ca/dapr/?lang=en Domoic Acid and ''Pseudo-nitzschia'' References]
*[http://www.marinespecies.org/HAB/aphia.php?p=taxlist/ IOC-UNESCO HAB Taxon list] 
*[https://web.archive.org/web/20120222143934/http://www.chbr.noaa.gov/pmn/ NOAA Phytoplankton Monitoring Network]
*[https://web.archive.org/web/20090627053359/http://www.nwfsc.noaa.gov/hab/habs_toxins/hab_species/pn/index.html Northwest Fisheries Science Center, NOAA]
*[https://web.archive.org/web/20060314021424/http://www.fathom.com/course/10701012/index.html Toxic Blooms: Understanding Red Tides], a seminar by the [[Organization:Woods Hole Oceanographic Institution|Woods Hole Oceanographic Institution]]
*[https://web.archive.org/web/20081227065719/http://www.chbr.noaa.gov/default.aspx?category=mb&pageName=biotoxin NOAA Marine Biotoxins Program], [[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]]
*[https://web.archive.org/web/20110720075322/http://calpreempt.ucsc.edu/index.htm California Program for Regional Enhanced Monitoring for PhycoToxins], California Department of Health Services and the [[Organization:University of California, Santa Cruz|University of California, Santa Cruz]]
*[https://web.archive.org/web/20070205171410/http://www.doh.wa.gov/ehp/sf/BiotoxinProgram.htm Washington State Shellfish Biotoxin Program]
*[http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artjul04/rvwdiatom1.html Series in Marine Phytoplankton: The genus ''Pseudo-nitzschia'']

{{Taxonbar|from=Q891709}}

[[Category:Bacillariales]]
[[Category:Diatom genera]]

{{Sourceattribution|Pseudo-nitzschia}}