Warnowia

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Warnowia
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Clade: Alveolata
Phylum: Myzozoa
Superclass: Dinoflagellata
Class: Dinophyceae
Order: Gymnodiniales
Family: Warnowiaceae
Genus: Warnowia
Lindemann, 1928 [1]
Type species
Warnowia fusus
(Schütt) Lindemann [1]

Warnowia is a genus of athecate dinoflagellates, characterized by having a very sophisticated photoreceptor organelle called the ocelloid. [1] This genus is dispersed worldwide but is scarce and difficult to find and nearly impossible to culture. As a result, the history and taxonomy of this genus are confusing at best, and many basic characteristics like its life cycle are still unknown. Still, Warnowia has drawn scientific interest as a unicellular organism with a fascinatingly complex photoreceptor system.

Contents

History of knowledge

The first description of the genus was in 1895 by Schütt, who called it Pouchetia , and designated the type species Pouchetia fusus. [2] In 1921, Kofoid & Swezy described many new species of Pouchetia in a collection of notes on free-living athecate dinoflagellates. [3] Although today it is commonly believed that many of the species described by Kofoid & Swezy are conspecific, their thorough and numerable descriptions of marine protists remain an admirable feat and a useful resource. [4] It was not until 1928 that the genus Warnowia was born, through the redesignation of many of the species in the genus Pouchetia by Lindemann. [5] Consequently, the type species Pouchetia fusus was renamed Warnowia fusus. In 1930, a new species of Warnowia (Warnowia dohrnii) was described by Zimmermann, indicating that the genus had been generally accepted in the scientific canon by that time. [5] In 1933, Schiller, like Lindemann before him, reclassified many of the remaining species in the Pouchetia genus as Warnowia. [5] The remaining Pouchetia species that were not classified as Warnowia were incorporated into the genera Protopsis , Nematodinium, and Erythropsidinium . [2] Today, the Pouchetia genus name is not accepted taxonomically, and is instead referred to as Nematodinium. [2] In the 1970s and '80s it was recognized that some organisms that had been designated species of Protopsis might have been life-cycle stages of Warnowia, and that Proterythropsis was congeneric with Warnowia. [1] In 2005, Gómez incorporated the genus Protopsis into Warnowia in his list of free-living marine dinoflagellates, and the genus finally reached the form that is currently accepted. [6]

Habitat and ecology

Warnowia is abundant in coastal and pelagic waters worldwide. [1] [7] The distribution of this genus stretches from warm temperate and tropical seas to the more northerly waters receiving warm currents from these warmer regions. [8] [9] In Europe, Warnowia has been sampled from the English Channel, Bay of Biscay, Mediterranean Sea and Nordic Seas. [7] [9] In North America, Warnowia has been isolated off of the western coast of Vancouver Island and off of the eastern coast of Massachusetts. [4] [10] Warnowia has also been collected from the southwest Atlantic Ocean, off the coast of Argentina. [11] Warnowia falls into the category of picoplankton, which constitutes a part of the picoeukaryotes community, and fills the ecological role of micro-consumers. [9] [4] Warnowia is rarely encountered in environmental samples. [12] [13] In addition to being found in coastal waters worldwide, Warnowia has a dynamic role in the planktonic community of the oligotrophic, nutrient-poor Sargasso Sea. [14] Warnowia represents a dominant component of the protists present in springtime in the Sargasso Sea. [14] In the summer, Warnowia is still present but is not the dominant group. [14] Seasonal shifts in Warnowia and other protists indicate a complex recycling food web in the Sargasso Sea, which helps to mitigate the low-nutrient availability of the open ocean. The presence of Warnowia in nutrient-rich coastal ecosystems as well as nutrient-poor pelagic ones suggests that it can survive under a wide range of nutrient availabilities, though it is unknown how they can be so dynamic.

Description of organism

Morphology and anatomy

Warnowia is a genus of heterotrophic athecate, or unarmored, dinoflagellates. [4] Some species of Warnowia are mixotrophic, so plastids (chloroplasts) may or may not be present. [1] They are unicellular, medium to very large (30-150 μm long) biflagellated cells. [1] The cingulum, the groove-like structure that runs around the equator of the organism, makes more than one loop, up to three. [1] Consequently, the sulcus, the groove that runs between the two hemispheres of the organism from the center of one side towards the posterior end of the cell, is twisted. [1] Like other dinoflagellates, in Warnowia, one flagellum (the transverse flagellum) circles the cingulum and the other (the longitudinal flagellum) lies along the sulcus and trails behind the cell. [4] Warnowia is characterized by a conspicuous photoreceptor organelle called the ocelloid located in the middle or posterior of the cell and directed ventral to anteriorly. [1] [4] Trichocysts, nematocysts, and pistons are absent, separating Warnowia from the closely related genera Nematodinium, Proterythropsis and Erythropsidinium. [1] [4] A tentacle-like posterior extension may or may not be present. [1] [4] The broad variation of apical groove, cingulum, sulcus, and ocelloid morphology suggests that the Warnowia genus may be an artificial assemblage of species rather than a genus, though this has yet to be confirmed by molecular phylogenetics. [4] The nucleus is of the dinokaryon type, with continuously condensed chromosomes as in other Dinokaryote dinoflagellates, [1] and located in the middle or upper half of the cell. [4]

The ocelloid

The ocelloid is a multilayered photoreceptor that is made up of subcellular components and is homologous to simpler eyespots found in other lineages of dinoflagellates. [13] The structure of the ocelloid is highly reminiscent of multicellular camera eyes that evolved independently in different lineages of metazoans, with a lens-like component that focuses light and a retina-like component that absorbs light. [4] The two main components of the ocelloid are the hyalosome and the melanosome. [4] The hyalosome is a translucent, layered cornea-like structure that is bounded at the base by iris-like constriction rings. [4] Like other non-plastid organelles, the hyalosome is thought to be synthesized by the cell and disassembled during cell division, then reassembled in each daughter cell. [4] The hyalosome appears to form a continuous network with mitochondria in the nearby cytoplasm, which is why the hyalosome is believed to be a derived mitochondrion. [13] The melanosome, also called the retinal body, is derived from photosynthetic plastids originating in red algae. [13] The melanosome is a highly organized and pigmented compartment that is separated by the hyalosome by a seawater chamber. [4] Thylakoids emerge when it becomes relatively unordered during cell division, which provides support for the plastid origin of the melanosome. [4] [13] Structural details of the ocelloid, such as the number and morphology of hyalosome constriction rings can be used to distinguish different species of Warnowia. [4] Although the morphological details of the ocelloid can be useful for some species differentiation, the structure and position of the ocelloid are malleable throughout the life cycle of Warnowia and so these characteristics are not concrete enough to be considered taxonomic criteria for delimiting species and genera. [4]

Life cycle

Heterotrophic protists such as Warnowia are particularly difficult to culture because culturing a heterotroph necessitates knowing its prey and culturing it consecutively. Due to its advertence to being cultured, the life stages of Warnowia have not yet been documented. There is speculation that some species of Warnowia form cysts prior to cell division because dormant Warnowia cysts have been found in the fossil record. [8] In addition, since the ocelloid re-organizes itself during cell division, it is thought that different life stages of Warnowia species have been previously mis-identified as unique species in a different genus. [1] This has been remedied to some degree, with the assimilation of the genus Protopsis into Warnowia, although it is possible that some life-stages of Warnowia remain mis-identified. [1]

Genetics and phylogeny

The genus Warnowia, along with Erythropsidinium , Pheopolykrikos, and Nematodinium, is part of the family Warnowiaceae, which is the group known as the warnowiids. [4] The warnowiids are characterized by their highly complex organelles, particularly the light-sensitive ocelloid. [4] This group forms a well-supported clade within the order Gymnodiniales sensu stricto, however the taxonomy within the warnowiids is poorly understood and highly problematic since these species are very difficult to culture and rare in the wild. [4] When using SSU data it was found that the genus most closely related to Warnowia was Erythropsinium. [12] The two form a monophyletic group that is sister to the Polykrikos clade within the Gymnodiniales. [12] There is little known about the molecular phylogeny and relationships between species within the genus Warnowia.

Fossil history

In 2001, off the coast of Norway and Portugal, surface sediment samples were found to contain cysts that were identified as Warnowiarosea once germinated. [8] The cysts were morphologically similar to acritarchs, which are organic microfossils that predate the presence of identifiable dinoflagellate cysts in the geological record. Acritarchs are present in the geological record dating back to 1.8 million years ago, from all time periods from the Proterozoic eon to the present. [15] The presence of identifiable Warnowia cysts and their morphological similarity to acritarchs supports the idea that athecate dinoflagellates may be represented by acritarchs in the ancient fossil record. [8]

List of species [16]

Related Research Articles

<span class="mw-page-title-main">Dinoflagellate</span> Unicellular algae with two flagella

The dinoflagellates are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they also are 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.

<span class="mw-page-title-main">Noctilucales</span> Order of single-celled organisms

The Noctilucales are an order of marine dinoflagellates. They differ from most others in that the mature cell is diploid and its nucleus does not show a dinokaryotic organization. They show gametic meiosis.

<span class="mw-page-title-main">Charles Atwood Kofoid</span> American zoologist

Charles Atwood Kofoid was an American zoologist known for his collection and classification of many new species of marine protozoans which established marine biology on a systematic basis.

<i>Peridinium</i> Genus of single-celled organisms

Peridinium is a genus of motile, marine and freshwater dinoflagellates. Their morphology is considered typical of the armoured dinoflagellates, and their form is commonly used in diagrams of a dinoflagellate's structure. Peridinium can range from 30 to 70 μm in diameter, and has very thick thecal plates.

<span class="mw-page-title-main">Gymnodiniales</span> Order of single-celled organisms

The Gymnodiniales are an order of dinoflagellates, of the class Dinophyceae. Members of the order are known as gymnodinioid or gymnodinoid. They are athecate, or lacking an armored exterior, and as a result are relatively difficult to study because specimens are easily damaged. Many species are part of the marine plankton and are of interest primarily due to being found in algal blooms. As a group the gymnodinioids have been described as "likely one of the least known groups of the open ocean phytoplankton."

<span class="mw-page-title-main">Dinophyceae</span> Class of single-celled organisms

Dinophyceae is a class of dinoflagellates.

<i>Dinophysis</i> Genus of single-celled organisms

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

<i>Gonyaulax</i> Genus of single-celled organisms

Gonyaulax is a genus of dinoflagellates with the type species Gonyaulax spinifera Diesing. Gonyaulax belongs to red dinoflagellates and commonly causes red tides. It can produce yesotoxins: for example, strains of Gonyaulax spinifera from New Zealand are yessotoxin producers.

<i>Alexandrium</i> (dinoflagellate) Genus of single-celled organisms

Alexandrium is a genus of dinoflagellates. It contains some of the dinoflagellate species most harmful to humans, because it produces toxic harmful algal blooms (HAB) that cause paralytic shellfish poisoning (PSP) in humans. There are about 30 species of Alexandrium that form a clade, defined primarily on morphological characters in their thecal plates.

<span class="mw-page-title-main">Ocelloid</span>

An ocelloid is a subcellular structure found in the family Warnowiaceae (warnowiids), which are members of a group of unicellular organisms known as dinoflagellates. The ocelloid is analogous in structure and function to the eyes of multicellular organisms, which focus, process and detect light. The ocelloid is much more complex than the eyespot, a light-sensitive structure also found in unicellular organisms, and is in fact one of the most complex known subcellular structures. It has been described as a striking example of convergent evolution.

<span class="mw-page-title-main">Warnowiaceae</span> Family of single-celled organisms

The Warnowiaceae are a family of athecate dinoflagellates. Members of the family are known as warnowiids. The family is best known for a light-sensitive subcellular structure known as the ocelloid, a highly complex arrangement of organelles with a structure directly analogous to the eyes of multicellular organisms. The ocelloid has been shown to be composed of multiple types of endosymbionts, namely mitochondria and at least one type of plastid.

<span class="mw-page-title-main">Piston (subcellular structure)</span>

A piston is a complex contractile organelle found in some dinoflagellates, namely the Erythropsidinium and Greuetodinium genera of the family Warnowiaceae. This group is also well known for possessing other unusually complex subcellular structures such as the ocelloid and nematocyst. Observations of Erythropsidinium samples reveal that the length of the piston is highly variable across specimens. The piston is known to be capable of repetitive and dramatic contractile motion; although its function is unknown, roles in locomotion, prey capture, and defense have been suggested.

<span class="mw-page-title-main">Polykrikaceae</span> Family of single-celled organisms

The Polykrikaceae are a family of athecate dinoflagellates of the order Gymnodiniales. Members of the family are known as polykrikoids. The family contains two genera: Polykrikos and Pheopolykrikos.

<i>Erythropsidinium</i> Genus of single-celled organisms

Erythropsidinium is a genus of dinoflagellates of the family Warnowiaceae.

<i>Polykrikos</i> Genus of single-celled organisms

Polykrikos is one of the genera of family Polykrikaceae that includes athecate pseudocolony-forming dinoflagellates. Polykrikos are characterized by a sophisticated ballistic apparatus, named the nematocyst-taeniocyst complex, which allows species to prey on a variety of organisms. Polykrikos have been found to regulate algal blooms as they feed on toxic dinoflagellates. However, there is also some data available on Polykrikos being toxic to fish.

Durinskia is a genus of dinoflagellates that can be found in freshwater and marine environments. This genus was created to accommodate its type species, Durinskia baltica, after major classification discrepancies were found. While Durinskia species appear to be typical dinoflagellates that are armored with cellulose plates called theca, the presence of a pennate diatom-derived tertiary endosymbiont is their most defining characteristic. This genus is significant to the study of endosymbiotic events and organelle integration since structures and organelle genomes in the tertiary plastids are not reduced. Like some dinoflagellates, species in Durinskia may cause blooms.

Torodinium (ˌtɔɹoʊˈdɪniəm) is a genus of unarmored dinoflagellates and comprises two species, Torodinium robustum and the type species Torodinium teredo. The establishment of Torodinium, as well as the characterization of the majority of its morphology, occurred in 1921 and further advances since have been slow. Lack of research is largely due to its extremely fragile and easily deformed nature, which also renders fossil records implausible. The genus was originally characterized by torsion of the sulcus and a posterior cingulum. Since then, new distinctive features have been discovered including an extremely reduced hyposome, a longitudinally ribbed episome, and a canal on the dextro-lateral side. Further investigation into the function of many anatomical features is still necessary for this genus.

<span class="mw-page-title-main">Gymnodiniaceae</span> Family of protists

Gymnodiniaceae is a family of dinoflagellates belonging to the order Gymnodiniales.

<i>Gyrodinium</i> Genus of protists

Gyrodinium is a genus of dinoflagellates belonging to the order Gymnodiniales within class Dinophyceae.

Lepidodinium is a genus of dinoflagellates belonging to the family Gymnodiniaceae. Lepidodinium is a genus of green dinoflagellates in the family Gymnodiniales. It contains two different species, Lepidodiniumchlorophorum and Lepidodinium viride. They are characterised by their green colour caused by a plastid derived from Pedinophyceae, a green algae group. This plastid has retained chlorophyll a and b, which is significant because it differs from the chlorophyll a and c usually observed in dinoflagellate peridinin plastids. They are the only known dinoflagellate genus to possess plastids derived from green algae. Lepidodinium chlorophorum is known to cause sea blooms, partially off the coast of France, which has dramatic ecological and economic consequences. Lepidodinium produces some of the highest volumes of Transparent Exopolymer Particles of any phytoplankton, which can contribute to bivalve death and the creation of anoxic conditions in blooms, as well as playing an important role in carbon cycling in the ocean.

References

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  3. ↑ Kofoid, Charles A.; Swezy, Olive (1921). The free-living unarmored dinoflagellata. Berkeley, Calif: University of California Press. doi:10.5962/bhl.title.24995.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Hoppenrath, Mona; Bachvaroff, Tsvetan R.; Handy, Sara M.; Delwiche, Charles F.; Leander, Brian S. (2009-05-25). "Molecular phylogeny of ocelloid-bearing dinoflagellates (Warnowiaceae) as inferred from SSU and LSU rDNA sequences". BMC Evolutionary Biology. 9 (1): 116. Bibcode:2009BMCEE...9..116H. doi: 10.1186/1471-2148-9-116 . ISSN   1471-2148. PMC   2694157 . PMID   19467154.
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  6. ↑ Gómez, F. (2005-05-31). "A list of free-living dinoflagellate species in the world's oceans". Acta Botanica Croatica. 64 (1): 129–212. ISSN   0365-0588.
  7. 1 2 Gailhard, I.; Gros, Ph; Durbec, J. P.; Beliaeff, B.; Belin, C.; Nézan, E.; Lassus, P. (2002-10-25). "Variability patterns of microphytoplankton communities along the French coasts". Marine Ecology Progress Series. 242: 39–50. Bibcode:2002MEPS..242...39G. doi: 10.3354/meps242039 . ISSN   0171-8630.
  8. 1 2 3 4 Ellegaard, Marianne; Dale, Barrie; Amorim, Ana (2001-11-01). "The acritarchous resting cyst of the athecate dinoflagellate Warnowia cf. rosea (Dinophyceae)". Phycologia. 40 (6): 542–546. Bibcode:2001Phyco..40..542E. doi:10.2216/i0031-8884-40-6-542.1. ISSN   0031-8884. S2CID   85649768.
  9. 1 2 3 Liu, Qian; Jiang, Yong; Wang, Qi; Wang, Min; McMinn, Andrew; Zhao, Qiannan; Xue, Chenglong; Wang, Xiaoyu; Dong, Jingyi; Yu, Yang; Han, Yuye; Zhao, Jinping (2019). "Using picoeukaryote communities to indicate the spatial heterogeneity of the Nordic Seas". Ecological Indicators. 107: 105582. doi:10.1016/j.ecolind.2019.105582. S2CID   199641196.
  10. ↑ Hulburt, Edward M. (1957). "The taxonomy of unarmored dinophyceae of shallow embayments on Cape Cod, Massachusetts". The Biological Bulletin. 112 (2): 196–219. doi:10.2307/1539198. ISSN   0006-3185. JSTOR   1539198.
  11. ↑ Akselman, Rut (1986). "Contribution to the knowledge of the family Warnowiaceae Lindemann (Class Dinophyceae) in the Southwestern Atlantic Ocean". Darwiniana. 27 (1–4): 9–17. ISSN   0011-6793. JSTOR   23217315.
  12. 1 2 3 Gómez, Fernando; López-García, Purificación; Moreira, David (2009). "Molecular Phylogeny of the Ocelloid-Bearing Dinoflagellates Erythropsidinium and Warnowia (Warnowiaceae, Dinophyceae)". Journal of Eukaryotic Microbiology. 56 (5): 440–445. doi:10.1111/j.1550-7408.2009.00420.x. PMID   19737196. S2CID   41132911.
  13. 1 2 3 4 5 Gavelis, Gregory S.; Hayakawa, Shiho; White III, Richard A.; Gojobori, Takashi; Suttle, Curtis A.; Keeling, Patrick J.; Leander, Brian S. (2015). "Eye-like ocelloids are built from different endosymbiotically acquired components". Nature. 523 (7559): 204–207. Bibcode:2015Natur.523..204G. doi:10.1038/nature14593. hdl: 10754/566109 . ISSN   1476-4687. PMID   26131935. S2CID   4462376.
  14. 1 2 3 Blanco-Bercial, Leocadio; Parsons, Rachel; Bolaños, Luis M.; Johnson, Rod; Giovannoni, Stephen J.; Curry, Ruth (2022). "The protist community traces seasonality and mesoscale hydrographic features in the oligotrophic Sargasso Sea". Frontiers in Marine Science. 9. doi: 10.3389/fmars.2022.897140 . ISSN   2296-7745.
  15. ↑ Rahman, Imran (2016-11-01). "PALAEONTOLOGY[online] | Article: Fossil Focus > Fossil Focus: Acritarchs". PALAEONTOLOGY[online]. Retrieved 2023-04-28.
  16. ↑ Gómez, F. (2012-06-04). "A checklist and classification of living dinoflagellates (Dinoflagellata, Alveolata)". CICIMAR Oceánides. 27 (1): 65–140. doi: 10.37543/oceanides.v27i1.111 . ISSN   2448-9123.
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