Dinophysis

Dinophysis
Scientific classification
Clade:	SAR
Infrakingdom:	Alveolata
Phylum:	Myzozoa
Superclass:	Dinoflagellata
Class:	Dinophyceae
Order:	Dinophysiales
Family:	Dinophysiaceae
Genus:	Dinophysis; Ehrenberg, 1839

Dinophysis is a genus of dinoflagellates common in tropical, temperate, coastal and oceanic waters.[1] It was first described in 1839 by Christian Gottfried Ehrenberg.[2]

Dinophysis are typically medium-sized cells (30-120 µm).[2] The structural plan and plate tabulation are conserved within the genus.[1] Dinophysis thecae are divided into halves by a sagittal fission suture.[1] There are five types of thecae ornamentation in this genus,[1] and those are a useful character for species identification.[1] Dinophysis mainly divide by binary fission.[1]

Dinophysis chloroplasts are usually rod-shaped or granular and yellow or brown colored.[1] Some Dinophysis spp. take up kleptoplastids when feeding. Toxic Dinophysis produce okadaic acid, dinophysistoxins, and pectenotoxins, which inhibit protein phosphatase and cause diarrhea.[3]

Background

The etymology of this genus name comes from Greek, Dino comes from "deinos" (δεινός)[4] meaning terrible[5] and "physis" (φύσις) meaning nature.[6]

The genus was first described in 1839 by Ehrenberg, which is why the holotype species of this genus is Dinophysis acuta Ehrenberg.[2] It has been found that what were considered different Dinophysis species might just be different life stages.[2]

Severe diarrheic shellfish poisoning breakouts in northeast Japan led to the identification of a Dinophysis species that produces toxins, Dinophysis fortii in 1976-77.[3] This genus is difficult to maintain in culture leading to challenges in gaining knowledge of these organisms.[3] Some Dinophysis spp. have kleptoplastids of cryptomonad origin, specifically from the cryptomonad Teleaulax amphioexia.[7] Dinophysis caudata have acquired these kleptoplastids by engulfing the ciliate Mesodinium rubrum which has engulfed T. amphioexia plastids.[7] Cryptomonad plastids have four membranes and a nucleomorph and are a product of secondary endosymbiosis.[7]

For years it was believed that Dinophysis did not have a sexual cycle.[3] However, it is now apparent that gamete cells can form in Dinophysis acuminata and D. acuta; this was found when small, spherical cells seemed to form inside larger ones.[3]

Habitat and ecology

The common habitat of Dinophysis is in tropical, temperate, coastal and oceanic waters.[1] Although most Dinophysis are marine and planktonic, some have been found in coastal lagoons[2]

Dinophysis caudata feed on ciliates, specifically Mesodinium rubrum through myzocytosis.[3] Picophytoplankton, bacteria, and cryptomonads are also likely part of the diet of Dinophysis.[3] For culture, Dinophysis are maintained on mixotrophic nutrition.[3] Although they are mixotrophic, they are mainly phagotrophic and photosynthesis is linked to kleptoplastids.[3]

Description of the organism

Morphology

The typical cell size of Dinophysis ranges from 30 to 120 µm, they are medium-sized cells.[2] It is possible for the cell size of Dinophysis to vary from large, vegetative cells to small, gamete-like cells.[3] Dinophysis have hypothecae that consist of two large plates, which take up most of the space of the theca, as well as some small platelets.[3] The genus is characterized by having 18 plates: four epithecal plates, two small apical plates, four sulcal plates, four cingular plates, and four hypothecal plates.[2] They have a cingulum, which is anteriorly positioned, and the cells are laterally compressed.[3] The structural plan and plate tabulation are conserved within the genus.[1] Dinophysis thecae are divided in halves by a sagittal fission suture.[1] Thecal ornamentation is a useful character for species identification.[1] There are five types of thecae ornamentation in this genus.[1] Type A is a smooth theca or a theca with shallow depressions, a single row of pores lines the anterior and posterior cingular lists and the margins of the large epithecal and hypothecal plates.[1] Type B has a more pitted thecal surface but has fewer pores; Type C is characterized by shallow hexagonal reticulation in the theca and a pore in the middle of each areola.[1] Type D exhibits large, spherical areolation in the thecal surface with pores in the center of every 3-5 areolae; type E is characteristic of laterally flattened Dinophysis and consists of a circular areolation thecal surface and a central pore in nearly all areolae.[1]

Plastids and kleptoplastids

Minute, usually rod-shaped or granular and yellow or brown colored chloroplasts are characteristic of Dinophysis.[1] The chloroplasts have stacks of three thylakoids and an internal pyrenoid.[1] In senescent cells, chloroplasts tend to aggregate in the middle and form orange patches.[1]

Some Dinophysis spp. likely possess plastids from cryptomonad origin, since the plastids are identical to those of the cryptophyte Teleaulax amphioxeia.[8] In this case, the process consisted in the engulfment (incomplete phagocytosis) of the ciliate M. rubrum which in turn engulfed a whole cryptomonad and now only the plastids remain.[8]

There has been debate surrounding whether the plastids of D. caudata are permanent or kleptoplastids.[9] It is now known that the plastids of D. caudata are kleptoplastids and the explanation for the discrepancy among molecular and ultrastructural data is due to structural modification during the acquisition of plastids through feeding.[9] When D. caudata was fed M. rubrum reddish-brown plastids, these were not digested in a food vacuole, rather they were transported to the periphery of the cell to join the rest of the plastids.[9] The plastids that were ingested are surrounded by membrane vesicles and transferred to the cytoplasm.[9] During plastid sequestration, the plastids see a change in morphology, the thylakoids of M. rubrum plastids become irregular and distended.[9] The change in pigment of the plastids is due to photoactivity, the change of low light to high light causes the plastids to turn green when there is no prey.[9] The cryptophyte nucleomorph found in M. rubrum is lost in D. caudata.[9] The final plastids of D. caudata appeared stellate and had clustered pyrenoids terminally positioned, their thylakoid membranes are placed in pairs.[9]

Life cycle

Dinophysis mainly divides asexually by binary fission.[1] For years it was believed that Dinophysis did not have a sexual cycle.[3] However, it is now apparent that gamete cells can form in D. acuminata and D. acuta; this was found when small, spherical cells seemed to form inside larger ones.[3] While the role of a sexual cycle in Dinophysis is not fully understood yet, there is a proposed model for how this works. In the proposed model, vegetative cells give rise to small motile cells (the smaller cells previously observed within the larger cells). The smaller cells then also become vegetative and act like gametes and after conjugation the cells divide and encyst.[10] The smaller cells that give rise to gametes tend to have thinner thecae and less developed cingular and sulcal lists.[10] They also are flagellated and swim, they use their flagella and lists to wrap around another gamete cell for conjugation.[10]

Although the gametes are part of a dimorphic sexual cycle, sex cysts do not play an active role in the seeding of Dinophysis populations.[3]

Pseudogenes

While toxic species of Dinophysis such as D. acuminata have a single gene for LSU rRNA, non-toxic species seem to have two distinct classes of LSU rRNA.[11] The difference between these two classes was a 70 bp deletion, indicating the shorter product might be a pseudogene.[11] The pseudogene can be used as a marker of D. acuminata and might conveniently serve as a marker of toxic and non-toxic strains[11] and bring more insight to the genetics of toxicity of Dinophysis.

Phylogenetics

Dinoflagellates are algae and according to recent phylogeny they are sister groups to ciliates and apicomplexans.[11] Most phylogenetic studies are done with sequences of both large and small ribosomal subunits and do not always agree with morphological studies based on thecal plates.[11] Sequencing of the small subunit of the ribosome of Dinophysis revealed very similar sequences in three species of Dinophysis (D. acuminata, D. norvegica and D. acuta), suggesting that photosynthetic Dinophysis have evolved recently.[11]

Practical importance

Dinophysis are a threat to shellfish aquaculture due to toxic lipophilic shellfish toxins that they produce.[3] Dinophysis have cryptophyte-like pigments and at least seven species of Dinophysis contain diarrheic shellfish toxins.[3]

Toxic Dinophysis produce okadaic acid, dinophysistoxins, and pectenotoxins, which inhibit protein phosphatase and produce diarrhea.[3] The more dominant the okadates are, the higher the impact on public health.[3] Toxins are secondary metabolites, and, in some cases, a single species can produce multiple types of toxins.[3] The production of these is controlled by both genetic factors and the environment.[3] The enzymes produced vary due to the environment in which Dinophysis grow.[3] The boreal seas, temperate seas and tropical seas are where most assemblages of Dinophysis that cause diarrheic shellfish poisoning occur.[3] Common features associated with toxic Dinophysis include: large sizes, highly developed cingular and sulcal lists and hypothecal processes.[3]

Species

Dinophysis acuminata Claparède & Lachmann, 1859
Dinophysis acuta Ehrenberg, 1839
Dinophysis acutissima Gaarder, 1954
Dinophysis alata E.G.Jørgensen
Dinophysis amandula (Balech) Sournia, 1973
Dinophysis amphora Balech, 1971
Dinophysis amygdala O.W.Paulsen
Dinophysis anabilis Abé, 1967
Dinophysis antarctica Balech, 1958
Dinophysis apicata (Kofoid & Skogsberg) Abé
Dinophysis apiculata Meunier, 1910
Dinophysis arctica Mereschkowsky, 1879
Dinophysis argus (Stein) Abé
Dinophysis balechii D.R.Norris & L.D.Berner, 1970
Dinophysis baltica (Paulsen) Kofoid & Skogsberg
Dinophysis bibulba Balech, 1971
Dinophysis biceps Schiller
Dinophysis braarudii (O.Nordli) Balech, 1967
Dinophysis capitulata Balech, 1967
Dinophysis carpentariae Wood, 1963
Dinophysis caudata Saville-Kent, 1881
Dinophysis collaris Kofoid & Michener, 1911
Dinophysis conjuncta D.Parra-Toriz, K.Esqueda-Lara & D.U.Hernández-Becerril, 2013
Dinophysis contracta (Kofoid & Skogsberg) Balech, 1973
Dinophysis cornuta (N.Peters) Balech, 1967
Dinophysis crassior Paulsen, 1949
Dinophysis curvata Schiller, 1933
Dinophysis cyrtoptera Balech, 1978
Dinophysis dens Pavillard, 1915
Dinophysis dentata Schiller, 1928
Dinophysis dubia Balech, 1978
Dinophysis equalantii Balech, 1971
Dinophysis exigua Kofoid & Skogsberg, 1928
Dinophysis expulsa Kofoid & Michener, 1911
Dinophysis fortii Pavillard, 1924
Dinophysis fortunata Sournia, 1973
Dinophysis gaarderae Sournia, 1973
Dinophysis granii Paulsen, 1949
Dinophysis hasleae Balech, 1973
Dinophysis hastata Stein, 1883
Dinophysis hyalina Wood, 1963
Dinophysis indica V.Srinivasan
Dinophysis infundibulum J. Schiller, 1928
Dinophysis intermedia Cleve, 1900
Dinophysis irregularis (Lebour) Balech, 1967
Dinophysis islandica Paulsen, 1949
Dinophysis joergersenii Kofoid & Skogsberg, 1928
Dinophysis lacrima (Gaarder) Balech, 1967
Dinophysis laevis Claparède & Lachmann, 1859
Dinophysis laticincta Balech, 1979
Dinophysis longialata Gran & Braarud, 1935
Dinophysis meteorii Böhm, 1933
Dinophysis meunieri Schiller, 1928
Dinophysis micheneri Sournia, 1973
Dinophysis micropleura Balech, 1971
Dinophysis micropterygia P.Dangeard, 1927
Dinophysis microstrigiliformis Abé, 1967
Dinophysis miles Cleve, 1900
Dinophysis mitroides Sournia, 1973
Dinophysis monacantha Kofoid & Skogsberg, 1928
Dinophysis moresbyensis Wood, 1963
Dinophysis mucronata (Kofoid & Skogsberg) Sournia, 1973
Dinophysis nasuta (Stein) Parke & Dixon, 1968
Dinophysis neolenticula Sournia, 1973
Dinophysis nias Karsten, 1907
Dinophysis norvegica Claparède & Lachmann, 1859
Dinophysis odiosa (Pavillard) Tai & Skogsberg, 1934
Dinophysis okamurae Kofoid & Skogsberg, 1928
Dinophysis opposita Wood, 1963
Dinophysis ovata Claparéde & Lachmann, 1859
Dinophysis oviformis Chen & Ni, 1988
Dinophysis ovum (F.Schütt) T.H.Abé
Dinophysis pacifica Wood, 1963
Dinophysis paralata Sournia, 1973
Dinophysis parva Schiller, 1928
Dinophysis parvula (Schütt) Balech, 1967
Dinophysis paulseni (Schiller) Balech
Dinophysis pedunculata
Dinophysis pellucidum Levring
Dinophysis perforata Sournia, 1973
Dinophysis phalacromoides (E.H.Jörgensen) F.Gomez, P.Lopez-Garcia & D.Moreira, 2011
Dinophysis pugiuncula (Jørgensen) Balech
Dinophysis pulchella (Lebour) Balech, 1967
Dinophysis punctata Jörgensen, 1923
Dinophysis pusilla Jørgensen, 1923
Dinophysis recurva Kofoid & Skogsberg, 1928
Dinophysis rete Sournia, 1973
Dinophysis reticulata Gaarder, 1954
Dinophysis robusta Gran & Braarud, 1935
Dinophysis rotundiformis L.-S.Tai & T.Skogsberg
Dinophysis rudgei Murray & Whitting, 1899
Dinophysis rugosa Kofoid & Michener, 1911
Dinophysis sacculus Stein, 1883
Dinophysis scabra Sournia, 1973
Dinophysis schilleri Sournia, 1973
Dinophysis schroederi Pavillard, 1909
Dinophysis schuettii Murray & Whitting, 1899
Dinophysis semen Meunier, 1910
Dinophysis siankanensis Almazán & Hernández-Becerril, 2002
Dinophysis similis Kofoid & Skogsberg, 1928
Dinophysis simplex Böhm, 1933
Dinophysis sourniai Balech, 1978
Dinophysis sphaerica Stein, 1883
Dinophysis sphaeroidea (J.Schiller) Balech
Dinophysis spinata (N.Peters) Balech, 1967
Dinophysis spinosa Rampi, 1950
Dinophysis subcircularis Paulsen, 1949
Dinophysis swezyae Kofoid & Skogsberg, 1928
Dinophysis symmetrica (Gaarder) Balech, 1967
Dinophysis tailisunii Chen & Ni, 1988
Dinophysis taylorii Hernandez-Becerril, 1992
Dinophysis tenuivelata Balech, 1973
Dinophysis thompsonii (E.J.F.Wood) Balech, 1967
Dinophysis trapezium Kofoid & Skogsberg, 1928
Dinophysis triacantha Kofoid, 1907
Dinophysis tripos Gourret, 1883
Dinophysis truncata Cleve, 1901
Dinophysis tuberculata Mangin, 1926
Dinophysis umbosa Schiller, 1928
Dinophysis uracantha Stein, 1883
Dinophysis uracanthoides (Jorgensen) F.Gomez, P.Lopez-Garcia & D.Moreira, 2011
Dinophysis urceola Kofoid & Skogsberg, 1928
Dinophysis vasta (F.Schütt) Balech
Dinophysis ventricosa Claparède & Lachmann
Dinophysis vermiculata C.-H.-G.Pouchet
Dinophysis vertex Meunier, 1910

References

Hallegraeff, G.M., Lucas, I.A.N. 1988: The marine dinoflagellate genus Dinophysis (Dinophyceae): photosynthetic, neritic and non-photosynthetic, oceanic species. Phycologia, 27: 25–42. 10.2216/i0031-8884-27-1-25.1
Ehrenberg, C.G., 1839. Über jetzt wirklich noch zahlreich lebende Thier-Arten der Kreideformatien der Erde. Königlich Preussische Akademie der Wissenschaften zu Berlin, Bericht über die zur Bekanntmachung geeigneten Verhandlungen, 1839, p.152-159.
Reguera, B. et al. 2012. Harmful Dinophysis species: A review. Harmful Algae, 14: 87–106. 10.1016/j.hal.2011.10.016
“Δεινός” Δεινός - Wiktionary, en.wiktionary.org/wiki/δεινός.
Anon, dino | Search Online Etymology Dictionary. Index. Available at: https://www.etymonline.com/search?q=dino [Accessed February 12, 2018].
“Physis” Wikipedia, Wikimedia Foundation, 20 Apr. 2018, en:Physis.
Kim, J. I., Yoon, H. S., Yi, G., Kim, H. S., Yih, W., & Shin, W. 2015: The plastid genome of the cryptomonad teleaulax amphioxeia. PLoS One, 10(6). doi:10.1371/journal.pone.0129284
Janson, S. & Granéli, E. 2003: Genetic Analysis of The psbA gene from Single Cells Indicates a Cryptomonad Origin of the Plastid in Dinophysis (Dinophyceae).” Phycologia, 42(5): 473–477. doi:10.2216/i0031-8884-42-5-473.1.
Kim, M., Nam, S. W., Shin, W., Coats, D. W. and Park, M. G. 2012: Dinophysis caudata (Dinophyceae) sequesters and retains plastids from the mixotrophic ciliate prey Mesodinium Rubrum. Journal of Phycology, 48: 569-579. doi:10.1111/j.1529-8817.2012.01150.x
Berland, Br, et al., 1995. Observations on possible life cycle stages of the dinoflagellates Dinophysis cf. acuminata, Dinophysis acuta and Dinophysis pavillardi. Aquatic Microbial Ecology, 9: 183–189.
Rehnstam-Holm, A.-S., Godhe, A. & Anderson, D.M., 2002. Molecular studies of Dinophysis (Dinophyceae) species from Sweden and North America. Phycologia, 41: 348–357.10.2216/i0031-8884-41-4-348.1