''Dinophysis'' is a genus of

dinoflagellate The Dinoflagellates (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they are also commo ...

AlgaeBase AlgaeBase is a global species database of information on all groups of algae, both seaweed, marine and freshwater algae, freshwater, as well as sea-grass. History AlgaeBase began in March 1996, founded by Michael D. Guiry, Michael Guiry. Text ...

''Dinophysis'' Ehrenberg, 1839
/ref> common in tropical, temperate, coastal and oceanic waters.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 It was first described in 1839 by

Christian Gottfried Ehrenberg Christian Gottfried Ehrenberg (19 April 1795 – 27 June 1876) was a German Natural history, naturalist, zoologist, Botany, botanist, comparative anatomist, geologist, and microscopy, microscopist. He is considered to be one of the most famous an ...

.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. Über noch zahlreich jetzt lebende Thierarten der Kreidebildung, nach Vorträgen in der Akademie der Wissenschaften zu Berlin in den Jahren 1839 und 1840, L. Voss, Leipzig
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p. 44ff ''Dinophysis'' are typically medium-sized cells (30-120 μm). The structural plan and plate tabulation are conserved within the genus. ''Dinophysis''

theca In biology, a theca (: thecae) is a sheath or a covering. Botany In botany, the theca is related to plant's flower anatomy. The theca of an angiosperm consists of a pair of microsporangia that are adjacent to each other and share a common ar ...

e are divided into halves by a

sagittal The sagittal plane (; also known as the longitudinal plane) is an anatomical plane that divides the body into right and left sections. It is perpendicular to the transverse plane, transverse and coronal plane, coronal planes. The plane may be in ...

fission suture. There are five types of thecae ornamentation in this genus, and those are a useful character for species identification. ''Dinophysis'' mainly divide by

binary fission Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two values (0 and 1) for each digit * Binary function, a function that takes two arguments * Binary operation, a mathematical o ...

. ''Dinophysis''

chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

s are usually rod-shaped or granular and yellow or brown colored. Some ''Dinophysis'' spp. take up kleptoplastids when feeding. Toxic ''Dinophysis'' produce

okadaic acid Okadaic acid, C44H68O13, is a toxin produced by several species of dinoflagellates. It is known to accumulate in both marine sponges and shellfish. One of the primary causes of diarrhetic shellfish poisoning, okadaic acid is a potent inhibitor of ...

, dinophysistoxins, and pectenotoxins, which inhibit protein phosphatase and cause

diarrhea Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...

.Reguera, B. et al. 2012. Harmful Dinophysis species: A review. Harmful Algae, 14: 87–106. 10.1016/j.hal.2011.10.016

Background

The etymology of this genus name comes from Greek, Dino comes from "" () meaning terrible and "" () meaning nature.“

Physis Physis (; ; pl. physeis, φύσεις) is a Greek philosophical, theological, and scientific term, usually translated into English—according to its Latin translation "natura"—as "nature". The term originated in ancient Greek philosophy, a ...

” Wikipedia, Wikimedia Foundation, 20 Apr. 2018, : en:Physis. The genus was first described in 1839 by Ehrenberg, which is why the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

species of this genus is '' Dinophysis acuta'' Ehrenberg. It has been found that what were considered different ''Dinophysis'' species might just be different life stages. Severe diarrheic shellfish poisoning breakouts in northeast

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

led to the identification of a ''Dinophysis'' species that produces toxins, '' Dinophysis fortii'' in 1976–77. This genus is difficult to maintain in culture leading to challenges in gaining knowledge of these organisms. Some ''Dinophysis'' spp. have kleptoplastids of

cryptomonad The cryptomonads (or cryptophytes) are a superclass of algae, most of which have plastids. They are traditionally considered a division of algae among phycologists, under the name of Cryptophyta. They are common in freshwater, and also occur ...

origin, specifically from the cryptomonad '' Teleaulax amphioxeia''.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). '' Dinophysis caudata'' have acquired these kleptoplastids by engulfing the

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagellum, eukaryotic flagella, but are in general shorter and present in much larger numbers, with a ...

'' Mesodinium rubrum'' which has engulfed ''T. amphioxeia'' plastids. Cryptomonad plastids have four membranes and a

nucleomorph Nucleomorphs are small, vestigial eukaryotic nuclei found between the inner and outer pairs of membranes in certain plastids. They are thought to be vestiges of red and green algal nuclei that were engulfed by a larger eukaryote. Because the nucl ...

and are a product of secondary endosymbiosis. For years it was believed that ''Dinophysis'' did not have a sexual cycle. However, it is now apparent that

gamete A gamete ( ) is a Ploidy#Haploid and monoploid, haploid cell that fuses with another haploid cell during fertilization in organisms that Sexual reproduction, reproduce sexually. Gametes are an organism's reproductive cells, also referred to as s ...

cells can form in '' Dinophysis acuminata'' and ''D. acuta''; this was found when small, spherical cells seemed to form inside larger ones.

Habitat and ecology

The common habitat of ''Dinophysis'' is in tropical, temperate, coastal and oceanic waters. Although most ''Dinophysis'' are marine and

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

ic, some have been found in coastal lagoons '' Dinophysis caudata'' feed on ciliates, specifically ''Mesodinium rubrum'' through

myzocytosis Myzocytosis (from Greek: myzein, (') meaning "to suck" and kytos (') meaning "container", hence referring to "cell") is a method of feeding found in some heterotrophic organisms. It is also called "cellular vampirism" as the predatory cell pierce ...

. Picophytoplankton, bacteria, and cryptomonads are also likely part of the diet of ''Dinophysis''. For culture, ''Dinophysis'' are maintained on

mixotroph A mixotroph is an organism that uses a mix of different sources of energy and carbon, instead of having a single trophic mode, on the continuum from complete autotrophy to complete heterotrophy. It is estimated that mixotrophs comprise more than ...

ic nutrition. Although they are mixotrophic, they are mainly phagotrophic and photosynthesis is linked to kleptoplastids.

Description of the organism

Morphology

The typical cell size of ''Dinophysis'' ranges from 30 to 120 μm, they are medium-sized cells. It is possible for the cell size of ''Dinophysis'' to vary from large, vegetative cells to small, gamete-like cells. ''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. 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. They have a cingulum, which is anteriorly positioned, and the cells are laterally compressed. The structural plan and plate tabulation are conserved within the genus. ''Dinophysis'' thecae are divided in halves by a sagittal fission suture. Thecal ornamentation is a useful character for species identification. There are five types of thecae ornamentation in this genus. 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. 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 The human areola (''areola mammae'', or ) is the pigmented area on the breast around the nipple. More generally, an areola is a small circular area on the Human body, body with a different histology from the surrounding Tissue (biology), tissue ...

. 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.

Plastids and kleptoplastids

Minute, usually rod-shaped or granular and yellow or brown colored

s are characteristic of ''Dinophysis''. The chloroplasts have stacks of three

thylakoid Thylakoids are membrane-bound compartments inside chloroplasts and cyanobacterium, cyanobacteria. They are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a #Membrane, thylakoid membrane surrounding a #Lumen, ...

s and an internal

pyrenoid Pyrenoids are sub-cellular phase-separated micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. ''An ...

. In senescent cells, chloroplasts tend to aggregate in the middle and form orange patches. Some ''Dinophysis'' spp. likely possess plastids from cryptomonad origin, since the plastids are identical to those of the cryptophyte '' Teleaulax amphioxeia''.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. In this case, the process consisted in the engulfment (incomplete

phagocytosis Phagocytosis () is the process by which a cell (biology), cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs ph ...

) of the ciliate ''M. rubrum'' which in turn engulfed a whole cryptomonad and now only the plastids remain. There has been debate surrounding whether the plastids of ''D. caudata'' are permanent or kleptoplastids.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 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. 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. The plastids that were ingested are surrounded by membrane vesicles and transferred to the cytoplasm. During plastid sequestration, the plastids see a change in morphology, the thylakoids of ''M. rubrum'' plastids become irregular and distended. 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. The cryptophyte nucleomorph found in ''M. rubrum'' is lost in ''D. caudata''. The final plastids of ''D. caudata'' appeared stellate and had clustered pyrenoids terminally positioned, their thylakoid membranes are placed in pairs.

Life cycle

''Dinophysis'' mainly divides asexually by binary fission. For years it was believed that ''Dinophysis'' did not have a sexual cycle. 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. 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.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. The smaller cells that give rise to gametes tend to have thinner thecae and less developed cingular and sulcal lists. They also are flagellated and swim, they use their flagella and lists to wrap around another gamete cell for conjugation. Although the gametes are part of a dimorphic sexual cycle, sex cysts do not play an active role in the seeding of ''Dinophysis'' populations.

Pseudogenes

While toxic species of ''Dinophysis'' such as ''D. acuminata'' have a single gene for

LSU rRNA Large subunit ribosomal ribonucleic acid (LSU rRNA) is the largest of the two major RNA components of the ribosome Ribosomes () are molecular machine, macromolecular machines, found within all cell (biology), cells, that perform Translation (b ...

, non-toxic species seem to have two distinct classes of LSU rRNA.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 The difference between these two classes was a 70 bp deletion, indicating the shorter product might be a

pseudogene Pseudogenes are nonfunctional segments of DNA that resemble functional genes. Pseudogenes can be formed from both protein-coding genes and non-coding genes. In the case of protein-coding genes, most pseudogenes arise as superfluous copies of fun ...

. The pseudogene can be used as a marker of ''D. acuminata'' and might conveniently serve as a marker of toxic and non-toxic strains 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. Most

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

studies are done with sequences of both large and small ribosomal subunits and do not always agree with morphological studies based on thecal plates. Sequencing of the small subunit of the

ribosome Ribosomes () are molecular machine, macromolecular machines, found within all cell (biology), cells, that perform Translation (biology), biological protein synthesis (messenger RNA translation). Ribosomes link amino acids together in the order s ...

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.

Practical importance

''Dinophysis'' are a threat to shellfish

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...

due to toxic

lipophilic Lipophilicity (from Greek language, Greek λίπος "fat" and :wikt:φίλος, φίλος "friendly") is the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such compounds are c ...

shellfish toxins that they produce. ''Dinophysis'' have cryptophyte-like pigments and at least seven species of ''Dinophysis'' contain diarrheic shellfish toxins. Toxic ''Dinophysis'' produce okadaic acid, dinophysistoxins, and pectenotoxins, which inhibit protein phosphatase and produce diarrhea. The more dominant the okadates are, the higher the impact on public health. Toxins are

secondary metabolite Secondary metabolites, also called ''specialised metabolites'', ''secondary products'', or ''natural products'', are organic compounds produced by any lifeform, e.g. bacteria, archaea, fungi, animals, or plants, which are not directly involved ...

s, and, in some cases, a single species can produce multiple types of toxins. The production of these is controlled by both genetic factors and the environment. The enzymes produced vary due to the environment in which ''Dinophysis'' grow. The boreal seas, temperate seas and tropical seas are where most assemblages of ''Dinophysis'' that cause diarrheic shellfish poisoning occur. Common features associated with toxic ''Dinophysis'' include: large sizes, highly developed cingular and sulcal lists and hypothecal processes.