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78-461: Dinophysis is a genus of dinoflagellates common in tropical, temperate, coastal and oceanic waters. It was first described in 1839 by Christian Gottfried Ehrenberg . Dinophysis are typically medium-sized cells (30-120 μm). The structural plan and plate tabulation are conserved within the genus. Dinophysis thecae are divided into halves by a sagittal fission suture. There are five types of thecae ornamentation in this genus, and those are

156-401: A cyst . Different types of dinoflagellate cysts are mainly defined based on morphological (number and type of layers in the cell wall) and functional (long- or short-term endurance) differences. These characteristics were initially thought to clearly distinguish pellicle (thin-walled) cysts from resting (double-walled) dinoflagellate cysts. The former were considered short-term (temporal) and

234-477: A haplontic life cycle , with the possible exception of Noctiluca and its relatives. The life cycle usually involves asexual reproduction by means of mitosis, either through desmoschisis or eleuteroschisis . More complex life cycles occur, more particularly with parasitic dinoflagellates. Sexual reproduction also occurs, though this mode of reproduction is only known in a small percentage of dinoflagellates. This takes place by fusion of two individuals to form

312-555: 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 common in freshwater habitats . Their populations vary with sea surface temperature , salinity , and depth. Many dinoflagellates are photosynthetic , but a large fraction of these are in fact mixotrophic , combining photosynthesis with ingestion of prey ( phagotrophy and myzocytosis ). In terms of number of species, dinoflagellates are one of

390-727: A nucleomorph 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 cells can form in Dinophysis acuminata and D. acuta ; this was found when small, spherical cells seemed to form inside larger ones. The common habitat of Dinophysis is in tropical, temperate, coastal and oceanic waters. Although most Dinophysis are marine and planktonic , some have been found in coastal lagoons Dinophysis caudata feed on ciliates, specifically Mesodinium rubrum through myzocytosis . Picophytoplankton , bacteria, and cryptomonads are also likely part of

468-560: A zygote , which may remain mobile in typical dinoflagellate fashion and is then called a planozygote. This zygote may later form a resting stage or hypnozygote , which is called a dinoflagellate cyst or dinocyst . After (or before) germination of the cyst, the hatchling undergoes meiosis to produce new haploid cells . Dinoflagellates appear to be capable of carrying out several DNA repair processes that can deal with different types of DNA damage . The life cycle of many dinoflagellates includes at least one nonflagellated benthic stage as

546-401: A dinokaryon are classified under Syndiniales . Although classified as eukaryotes , the dinoflagellate nuclei are not characteristically eukaryotic, as some of them lack histones and nucleosomes , and maintain continually condensed chromosomes during mitosis . The dinoflagellate nucleus was termed 'mesokaryotic' by Dodge (1966), due to its possession of intermediate characteristics between

624-401: A lack of diversity may occur in a bloom is through a reduction in predation and a decreased competition. The first may be achieved by having predators reject the dinoflagellate, by, for example, decreasing the amount of food it can eat. This additionally helps prevent a future increase in predation pressure by causing predators that reject it to lack the energy to breed. A species can then inhibit

702-460: A little above the breasts' contour. Pregnancy can cause enlargement of the Areola tissue and of Montgomery glands or tubercles. Breastfeeding by the baby stimulates slowly and rapidly adapting mechanoreceptors that are densely packed around the areolar region. Paget's disease of the breast is a malignant condition that outwardly may have the appearance of eczema , with skin changes involving

780-458: A novel, dominant family of nuclear proteins that appear to be of viral origin, thus are called Dinoflagellate viral nucleoproteins (DVNPs) which are highly basic, bind DNA with similar affinity to histones, and occur in multiple posttranslationally modified forms. Dinoflagellate nuclei remain condensed throughout interphase rather than just during mitosis , which is closed and involves a uniquely extranuclear mitotic spindle . This sort of nucleus

858-510: A plastid derived from secondary endosymbiosis of red algae, however dinoflagellates with plastids derived from green algae and tertiary endosymbiosis of diatoms have also been discovered. Similar to other photosynthetic organisms, dinoflagellates contain chlorophylls a and c2 and the carotenoid beta-carotene. Dinoflagellates also produce the xanthophylls including peridinin , dinoxanthin , and diadinoxanthin . These pigments give many dinoflagellates their typical golden brown color. However,

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936-567: A potent neurotoxin that immobilizes its prey upon contact. When K. arminger are present in large enough quantities, they are able to cull whole populations of its copepods prey. The feeding mechanisms of the oceanic dinoflagellates remain unknown, although pseudopodial extensions were observed in Podolampas bipes . Dinoflagellate blooms are generally unpredictable, short, with low species diversity, and with little species succession. The low species diversity can be due to multiple factors. One way

1014-852: A result of the abundant nutrients in the water. Although the resulting red waves are an interesting visual phenomenon, they contain toxins that not only affect all marine life in the ocean, but the people who consume them as well. A specific carrier is shellfish . This can introduce both nonfatal and fatal illnesses. One such poison is saxitoxin , a powerful paralytic neurotoxin . Human inputs of phosphate further encourage these red tides, so strong interest exists in learning more about dinoflagellates, from both medical and economic perspectives. Dinoflagellates are known to be particularly capable of scavenging dissolved organic phosphorus for P-nutrient, several HAS species have been found to be highly versatile and mechanistically diversified in utilizing different types of DOPs. The ecology of harmful algal blooms

1092-419: 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

1170-712: A single gene for LSU rRNA , non-toxic species seem to have two distinct classes of LSU rRNA. The difference between these two classes was a 70 bp deletion, indicating the shorter product might be a pseudogene . 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 . Dinoflagellates are algae and according to recent phylogeny they are sister groups to ciliates and apicomplexans . 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. Sequencing of

1248-531: A total of 2,294 living dinoflagellate species, which includes marine, freshwater, and parasitic dinoflagellates. A rapid accumulation of certain dinoflagellates can result in a visible coloration of the water, colloquially known as red tide (a harmful algal bloom ), which can cause shellfish poisoning if humans eat contaminated shellfish. Some dinoflagellates also exhibit bioluminescence , primarily emitting blue-green light, which may be visible in oceanic areas under certain conditions. The term "dinoflagellate"

1326-411: A turning force. The longitudinal flagellum is relatively conventional in appearance, with few or no hairs. It beats with only one or two periods to its wave. The flagella lie in surface grooves: the transverse one in the cingulum and the longitudinal one in the sulcus, although its distal portion projects freely behind the cell. In dinoflagellate species with desmokont flagellation (e.g., Prorocentrum ),

1404-561: A useful character for species identification. Dinophysis mainly divide by binary fission . Dinophysis chloroplasts are usually rod-shaped or granular and yellow or brown colored. Some Dinophysis spp. take up kleptoplastids when feeding. Toxic Dinophysis produce okadaic acid , dinophysistoxins , and pectenotoxins , which inhibit protein phosphatase and cause diarrhea . The etymology of this genus name comes from Greek, Dino comes from " deinos " ( δεινός ) meaning terrible and " physis " ( φύσις ) meaning nature. The genus

1482-649: Is a combination of the Greek dinos and the Latin flagellum . Dinos means "whirling" and signifies the distinctive way in which dinoflagellates were observed to swim. Flagellum means "whip" and this refers to their flagella . In 1753, the first modern dinoflagellates were described by Henry Baker as "Animalcules which cause the Sparkling Light in Sea Water", and named by Otto Friedrich Müller in 1773. The term derives from

1560-406: Is around 28.0 mm (1.1 in). Sexually mature women have an average of 38.1 mm (1.5 in), but sizes can exceed 100 mm (4 in). Lactating women, and women with particularly large breasts, may have even larger areolae. A function of the specialized dermis of the areola is to protect the regular breast skin from wear, cracking , and irritation. Infants sometimes create trauma to

1638-448: Is called a red tide , from the color the bloom imparts to the water. Some colorless dinoflagellates may also form toxic blooms, such as Pfiesteria . Some dinoflagellate blooms are not dangerous. Bluish flickers visible in ocean water at night often come from blooms of bioluminescent dinoflagellates, which emit short flashes of light when disturbed. A red tide occurs because dinoflagellates are able to reproduce rapidly and copiously as

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1716-630: Is characterized by shallow hexagonal reticulation in the theca and a pore in the middle of each areola . 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. Minute, usually rod-shaped or granular and yellow or brown colored chloroplasts are characteristic of Dinophysis . The chloroplasts have stacks of three thylakoids and an internal pyrenoid . In senescent cells , chloroplasts tend to aggregate in

1794-423: Is difficult to maintain in culture leading to challenges in gaining knowledge of these organisms. Some Dinophysis spp. have kleptoplastids of cryptomonad origin, specifically from the cryptomonad Teleaulax amphioxeia . Dinophysis caudata have acquired these kleptoplastids by engulfing the ciliate Mesodinium rubrum which has engulfed T. amphioxeia plastids. Cryptomonad plastids have four membranes and

1872-412: Is extensively studied. At night, water can have an appearance of sparkling light due to the bioluminescence of dinoflagellates. More than 18 genera of dinoflagellates are bioluminescent, and the majority of them emit a blue-green light. These species contain scintillons , individual cytoplasmic bodies (about 0.5 μm in diameter) distributed mainly in the cortical region of the cell, outpockets of

1950-556: 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

2028-427: Is pH sensitive. When the pH drops, luciferase changes its shape, allowing luciferin, more specifically tetrapyrrole, to bind. Dinoflagellates can use bioluminescence as a defense mechanism. They can startle their predators by their flashing light or they can ward off potential predators by an indirect effect such as the "burglar alarm". The bioluminescence attracts attention to the dinoflagellate and its attacker, making

2106-793: Is sufficient for nutrition, are classified as amphitrophic. If both forms are required, the organisms are mixotrophic sensu stricto . Some free-living dinoflagellates do not have chloroplasts, but host a phototrophic endosymbiont. A few dinoflagellates may use alien chloroplasts (cleptochloroplasts), obtained from food ( kleptoplasty ). Some dinoflagellates may feed on other organisms as predators or parasites. Food inclusions contain bacteria, bluegreen algae, diatoms, ciliates, and other dinoflagellates. Mechanisms of capture and ingestion in dinoflagellates are quite diverse. Several dinoflagellates, both thecate (e.g. Ceratium hirundinella , Peridinium globulus ) and nonthecate (e.g. Oxyrrhis marina , Gymnodinium sp. and Kofoidinium spp. ), draw prey to

2184-529: The International Code of Botanical Nomenclature (ICBN, now renamed as ICN) and the International Code of Zoological Nomenclature (ICZN). About half of living dinoflagellate species are autotrophs possessing chloroplasts and half are nonphotosynthesising heterotrophs. The peridinin dinoflagellates, named after their peridinin plastids, appear to be ancestral for the dinoflagellate lineage. Almost half of all known species have chloroplasts, which are either

2262-603: The flagellate order Dinoflagellida. Botanists treated them as a division of algae, named Pyrrophyta or Pyrrhophyta ("fire algae"; Greek pyrr(h)os , fire) after the bioluminescent forms, or Dinophyta . At various times, the cryptomonads , ebriids , and ellobiopsids have been included here, but only the last are now considered close relatives. Dinoflagellates have a known ability to transform from noncyst to cyst-forming strategies, which makes recreating their evolutionary history extremely difficult. Dinoflagellates are unicellular and possess two dissimilar flagella arising from

2340-798: The okadates are, the higher the impact on public health. Toxins are secondary metabolites , 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. Dinoflagellate The dinoflagellates (from Ancient Greek δῖνος ( dînos )  'whirling' and Latin flagellum  'whip, scourge') are

2418-455: The theca or lorica , as opposed to athecate ("nude") dinoflagellates. These occur in various shapes and arrangements, depending on the species and sometimes on the stage of the dinoflagellate. Conventionally, the term tabulation has been used to refer to this arrangement of thecal plates . The plate configuration can be denoted with the plate formula or tabulation formula. Fibrous extrusomes are also found in many forms. A transverse groove,

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2496-468: The 350 described freshwater species and a little more than 10% of the known marine species. Dinoflagellates are alveolates possessing two flagella , the ancestral condition of bikonts . About 1,555 species of free-living marine dinoflagellates are currently described. Another estimate suggests about 2,000 living species, of which more than 1,700 are marine (free-living, as well as benthic) and about 220 are from fresh water. The latest estimates suggest

2574-479: The Greek word δῖνος ( dînos ), meaning whirling, and Latin flagellum , a diminutive term for a whip or scourge. In the 1830s, the German microscopist Christian Gottfried Ehrenberg examined many water and plankton samples and proposed several dinoflagellate genera that are still used today including Peridinium, Prorocentrum , and Dinophysis . These same dinoflagellates were first defined by Otto Bütschli in 1885 as

2652-528: The United States, Central Florida is home to the Indian River Lagoon which is abundant with dinoflagellates in the summer and bioluminescent ctenophore in the winter. Dinoflagellates produce characteristic lipids and sterols. One of these sterols is typical of dinoflagellates and is called dinosterol . Dinoflagellate theca can sink rapidly to the seafloor in marine snow . Dinoflagellates have

2730-451: The ability of the dinoflagellate to prey upon larger copepods. Toxic strains of K. veneficum produce karlotoxin that kills predators who ingest them, thus reducing predatory populations and allowing blooms of both toxic and non-toxic strains of K. veneficum . Further, the production of karlotoxin enhances the predatory ability of K. veneficum by immobilizing its larger prey. K. arminger are more inclined to prey upon copepods by releasing

2808-455: The advantages of recombination and sexuality, such that in fungi, for example, complex combinations of haploid and diploid cycles have evolved that include asexual and sexual resting stages. However, in the general life cycle of cyst-producing dinoflagellates as outlined in the 1960s and 1970s, resting cysts were assumed to be the fate of sexuality, which itself was regarded as a response to stress or unfavorable conditions. Sexuality involves

2886-476: The cells divide and encyst. 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. While toxic species of Dinophysis such as D. acuminata have

2964-562: The coiled DNA areas of prokaryotic bacteria and the well-defined eukaryotic nucleus. This group, however, does contain typically eukaryotic organelles , such as Golgi bodies, mitochondria, and chloroplasts. Jakob Schiller (1931–1937) provided a description of all the species, both marine and freshwater, known at that time. Later, Alain Sournia (1973, 1978, 1982, 1990, 1993) listed the new taxonomic entries published after Schiller (1931–1937). Sournia (1986) gave descriptions and illustrations of

3042-416: The conclusion that encystment is associated with sexual reproduction. These observations also gave credence to the idea that microalgal encystment is essentially a process whereby zygotes prepare themselves for a dormant period. Because the resting cysts studied until that time came from sexual processes, dormancy was associated with sexuality, a presumption that was maintained for many years. This attribution

3120-480: The cysts remain in the sediment layer during conditions unfavorable for vegetative growth and, from there, reinoculate the water column when favorable conditions are restored. Indeed, during dinoflagellate evolution the need to adapt to fluctuating environments and/or to seasonality is thought to have driven the development of this life cycle stage. Most protists form dormant cysts in order to withstand starvation and UV damage. However, there are enormous differences in

3198-508: The diet of Dinophysis . For culture, Dinophysis are maintained on mixotrophic nutrition. Although they are mixotrophic, they are mainly phagotrophic and photosynthesis is linked to kleptoplastids. 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

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3276-482: The dinoflagellates Karenia brevis , Karenia mikimotoi , and Karlodinium micrum have acquired other pigments through endosymbiosis, including fucoxanthin . This suggests their chloroplasts were incorporated by several endosymbiotic events involving already colored or secondarily colorless forms. The discovery of plastids in the Apicomplexa has led some to suggest they were inherited from an ancestor common to

3354-529: The fusion of haploid gametes from motile planktonic vegetative stages to produce diploid planozygotes that eventually form cysts, or hypnozygotes , whose germination is subject to both endogenous and exogenous controls. Endogenously, a species-specific physiological maturation minimum period (dormancy) is mandatory before germination can occur. Thus, hypnozygotes were also referred to as "resting" or "resistant" cysts, in reference to this physiological trait and their capacity following dormancy to remain viable in

3432-459: The genus Symbiodinium ). The association between Symbiodinium and reef-building corals is widely known. However, endosymbiontic Zooxanthellae inhabit a great number of other invertebrates and protists, for example many sea anemones , jellyfish , nudibranchs , the giant clam Tridacna , and several species of radiolarians and foraminiferans . Many extant dinoflagellates are parasites (here defined as organisms that eat their prey from

3510-401: The growth of its competitors, thus achieving dominance. Dinoflagellates sometimes bloom in concentrations of more than a million cells per millilitre. Under such circumstances, they can produce toxins (generally called dinotoxins ) in quantities capable of killing fish and accumulating in filter feeders such as shellfish , which in turn may be passed on to people who eat them. This phenomenon

3588-721: The inside, i.e. endoparasites , or that remain attached to their prey for longer periods of time, i.e. ectoparasites). They can parasitize animal or protist hosts. Protoodinium, Crepidoodinium, Piscinoodinium , and Blastodinium retain their plastids while feeding on their zooplanktonic or fish hosts. In most parasitic dinoflagellates, the infective stage resembles a typical motile dinoflagellate cell. Three nutritional strategies are seen in dinoflagellates: phototrophy , mixotrophy , and heterotrophy . Phototrophs can be photoautotrophs or auxotrophs . Mixotrophic dinoflagellates are photosynthetically active, but are also heterotrophic. Facultative mixotrophs, in which autotrophy or heterotrophy

3666-485: The largest groups of marine eukaryotes, although substantially smaller than diatoms . Some species are endosymbionts of marine animals and play an important part in the biology of coral reefs . Other dinoflagellates are unpigmented predators on other protozoa, and a few forms are parasitic (for example, Oodinium and Pfiesteria ). Some dinoflagellates produce resting stages, called dinoflagellate cysts or dinocysts , as part of their lifecycles; this occurs in 84 of

3744-432: The latter long-term (resting) cysts. However, during the last two decades further knowledge has highlighted the great intricacy of dinoflagellate life histories. More than 10% of the approximately 2000 known marine dinoflagellate species produce cysts as part of their life cycle (see diagram on the right). These benthic phases play an important role in the ecology of the species, as part of a planktonic-benthic link in which

3822-498: The main cell vacuole. They contain dinoflagellate luciferase , the main enzyme involved in dinoflagellate bioluminescence, and luciferin , a chlorophyll-derived tetrapyrrole ring that acts as the substrate to the light-producing reaction. The luminescence occurs as a brief (0.1 sec) blue flash (max 476 nm) when stimulated, usually by mechanical disturbance. Therefore, when mechanically stimulated—by boat, swimming, or waves, for example—a blue sparkling light can be seen emanating from

3900-405: The main phenotypic, physiological and resistance properties of each dinoflagellate species cysts. Unlike in higher plants most of this variability, for example in dormancy periods, has not been proven yet to be attributed to latitude adaptation or to depend on other life cycle traits. Thus, despite recent advances in the understanding of the life histories of many dinoflagellate species, including

3978-1151: The marine genera of dinoflagellates, excluding information at the species level. The latest index is written by Gómez. English-language taxonomic monographs covering large numbers of species are published for the Gulf of Mexico, the Indian Ocean, the British Isles, the Mediterranean and the North Sea. The main source for identification of freshwater dinoflagellates is the Süsswasser Flora . Calcofluor-white can be used to stain thecal plates in armoured dinoflagellates. Dinoflagellates are found in all aquatic environments: marine, brackish, and fresh water, including in snow or ice. They are also common in benthic environments and sea ice. All Zooxanthellae are dinoflagellates and most of them are members within Symbiodiniaceae (e.g.

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4056-426: 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 . 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. There has been debate surrounding whether

4134-451: The nipple and areolae by latching-on . Rated according to the Tanner scale of female physical development, the areolae enlarge during stage 3, but they show no separation of contour. During stage 4, the areolae and papillae rise above breast level and form secondary mounds. By stage 5, the breasts have fully developed. As this has resulted in recession of the areolae, the papillae may reach

4212-476: The nipple area more visible to the infant. Hyperpigmentation occurs in most women during the second stage of pregnancy, leading to a temporarily darker shade. The size and shape of areolae and nipples are also highly variable, with those of women usually being larger than those of men and prepubescent girls. Human areolae are mostly circular in shape, but many women have large areolae that are noticeably elliptical . The average diameter of male areolae

4290-522: The only other dinoflagellate genera known to use this particular feeding mechanism. Katodinium (Gymnodinium) fungiforme , commonly found as a contaminant in algal or ciliate cultures, feeds by attaching to its prey and ingesting prey cytoplasm through an extensible peduncle. Two related species, polykrikos kofoidii and neatodinium, shoots out a harpoon-like organelle to capture prey. Some mixotrophic dinoflagellates are able to produce neurotoxins that have anti-grazing effects on larger copepods and enhance

4368-408: The order Gymnodiniales , suborder Actiniscineae . The formation of thecal plates has been studied in detail through ultrastructural studies. 'Core dinoflagellates' ( dinokaryotes ) have a peculiar form of nucleus , called a dinokaryon , in which the chromosomes are attached to the nuclear membrane . These carry reduced number of histones . In place of histones, dinoflagellate nuclei contain

4446-464: The original peridinin plastids or new plastids acquired from other lineages of unicellular algae through endosymbiosis. The remaining species have lost their photosynthetic abilities and have adapted to a heterotrophic, parasitic or kleptoplastic lifestyle. Most (but not all) dinoflagellates have a dinokaryon , described below (see: Life cycle , below). Dinoflagellates with a dinokaryon are classified under Dinokaryota , while dinoflagellates without

4524-413: 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

4602-434: The plastids of D. caudata are permanent or kleptoplastids. 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

4680-418: 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. Dinophysis mainly divides asexually by binary fission. For years it was believed that Dinophysis did not have a sexual cycle. However, it

4758-641: The predator more vulnerable to predation from higher trophic levels. Bioluminescent dinoflagellate ecosystem bays are among the rarest and most fragile, with the most famous ones being the Bioluminescent Bay in La Parguera, Lajas , Puerto Rico; Mosquito Bay in Vieques, Puerto Rico ; and Las Cabezas de San Juan Reserva Natural Fajardo, Puerto Rico . Also, a bioluminescent lagoon is near Montego Bay, Jamaica, and bioluminescent harbors surround Castine, Maine. Within

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4836-414: The role of cyst stages, many gaps remain in knowledge about their origin and functionality. Recognition of the capacity of dinoflagellates to encyst dates back to the early 20th century, in biostratigraphic studies of fossil dinoflagellate cysts. Paul Reinsch was the first to identify cysts as the fossilized remains of dinoflagellates. Later, cyst formation from gamete fusion was reported, which led to

4914-406: The sea surface. Dinoflagellate bioluminescence is controlled by a circadian clock and only occurs at night. Luminescent and nonluminescent strains can occur in the same species. The number of scintillons is higher during night than during day, and breaks down during the end of the night, at the time of maximal bioluminescence. The luciferin-luciferase reaction responsible for the bioluminescence

4992-431: The sediments for long periods of time. Exogenously, germination is only possible within a window of favorable environmental conditions. Yet, with the discovery that planozygotes were also able to divide it became apparent that the complexity of dinoflagellate life cycles was greater than originally thought. Following corroboration of this behavior in several species, the capacity of dinoflagellate sexual phases to restore

5070-626: 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. Dinophysis are a threat to shellfish aquaculture due to toxic lipophilic 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

5148-469: The smallest known eye. Some athecate species have an internal skeleton consisting of two star-like siliceous elements that has an unknown function, and can be found as microfossils . Tappan gave a survey of dinoflagellates with internal skeletons . This included the first detailed description of the pentasters in Actiniscus pentasterias , based on scanning electron microscopy . They are placed within

5226-401: The so-called cingulum (or cigulum) runs around the cell, thus dividing it into an anterior (episoma) and posterior (hyposoma). If and only if a theca is present, the parts are called epitheca and hypotheca, respectively. Posteriorly, starting from the transverse groove, there is a longitudinal furrow called the sulcus. The transverse flagellum strikes in the cingulum, the longitudinal flagellum in

5304-439: 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

5382-406: The sulcal region of the cell (either via water currents set up by the flagella or via pseudopodial extensions) and ingest the prey through the sulcus. In several Protoperidinium spp., e.g. P. conicum , a large feeding veil—a pseudopod called the pallium—is extruded to capture prey which is subsequently digested extracellularly (= pallium-feeding). Oblea , Zygabikodinium , and Diplopsalis are

5460-452: The sulcus. Together with various other structural and genetic details, this organization indicates a close relationship between the dinoflagellates, the Apicomplexa , and ciliates , collectively referred to as the alveolates . Dinoflagellate tabulations can be grouped into six "tabulation types": gymnodinoid , suessoid , gonyaulacoid – peridinioid , nannoceratopsioid , dinophysioid , and prorocentroid . Most Dinoflagellates have

5538-424: The tip of the lactiferous ducts , from which milk is released during lactation . The other small openings in the areola are sebaceous glands , also known as areolar glands . The areolae can range from pink to red to brown to dark brown or nearly black, but generally tend to be paler among people with lighter skin tones and darker among people with darker skin tones. A reason for the differing color may be to make

5616-415: The two flagella are differentiated as in dinokonts, but they are not associated with grooves. Dinoflagellates have a complex cell covering called an amphiesma or cortex, composed of a series of membranes, flattened vesicles called alveoli (= amphiesmal vesicles) and related structures. In thecate ("armoured") dinoflagellates, these support overlapping cellulose plates to create a sort of armor called

5694-456: The two groups, but none of the more basal lines has them. All the same, the dinoflagellate cell consists of the more common organelles such as rough and smooth endoplasmic reticulum , Golgi apparatus , mitochondria , lipid and starch grains, and food vacuoles . Some have even been found with a light-sensitive organelle, the eyespot or stigma , or a larger nucleus containing a prominent nucleolus . The dinoflagellate Erythropsidinium has

5772-555: The vegetative phase, bypassing cyst formation, became well accepted. Further, in 2006 Kremp and Parrow showed the dormant resting cysts of the Baltic cold water dinoflagellates Scrippsiella hangoei and Gymnodinium sp. were formed by the direct encystment of haploid vegetative cells, i.e., asexually. In addition, for the zygotic cysts of Pfiesteria piscicida dormancy was not essential. Areola The mature human female nipple has several small openings arranged radially around

5850-506: The ventral cell side (dinokont flagellation). They have a ribbon-like transverse flagellum with multiple waves that beats to the cell's left, and a more conventional one, the longitudinal flagellum, that beats posteriorly. The transverse flagellum is a wavy ribbon in which only the outer edge undulates from base to tip, due to the action of the axoneme which runs along it. The axonemal edge has simple hairs that can be of varying lengths. The flagellar movement produces forward propulsion and also

5928-426: Was coincident with evolutionary theories about the origin of eukaryotic cell fusion and sexuality, which postulated advantages for species with diploid resting stages, in their ability to withstand nutrient stress and mutational UV radiation through recombinational repair, and for those with haploid vegetative stages, as asexual division doubles the number of cells. Nonetheless, certain environmental conditions may limit

6006-431: Was first described in 1839 by Ehrenberg, which is why the holotype 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 led to the identification of a Dinophysis species that produces toxins, Dinophysis fortii in 1976–77. This genus

6084-536: Was once considered to be an intermediate between the nucleoid region of prokaryotes and the true nuclei of eukaryotes , so were termed " mesokaryotic ", but now are considered derived rather than primitive traits (i. e. ancestors of dinoflagellates had typical eukaryotic nuclei). In addition to dinokaryotes, DVNPs can be found in a group of basal dinoflagellates (known as Marine Alveolates , "MALVs") that branch as sister to dinokaryotes ( Syndiniales ). Dinoflagellates are protists and have been classified using both

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