Symbiodinium
Symbiodinium | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Clade: | Diaphoretickes |
Clade: | SAR |
Clade: | Alveolata |
Phylum: | Myzozoa |
Superclass: | Dinoflagellata |
Class: | Dinophyceae |
Order: | Suessiales |
Family: | Symbiodiniaceae |
Genus: | Symbiodinium Freudenthal, 1962 [1] |
Species | |
Symbiodinium is a
Symbiodinium are colloquially called zooxanthellae, and animals symbiotic with algae in this genus are said to be "zooxanthellate". The term was loosely used to refer to any golden-brown endosymbionts, including diatoms and other dinoflagellates. Continued use of the term in the scientific literature is discouraged because of the confusion caused by overly generalizing taxonomically diverse symbiotic relationships.[2]
In 2018, the systematics of
Intracellular symbionts
Many Symbiodinium species are known primarily for their role as
Natural services and economic value
Symbiodinium is one of the most studied symbionts. Their mutualistic relationships with reef-building corals form the basis of a highly diverse and productive
Coral bleaching
The study of Symbiodinium biology is driven largely by a desire to understand global coral reef decline. A chief mechanism for widespread reef degradation has been stress-induced
The symbiosis Symbodinium-coral could provide higher resistance to multiple stress (desiccation, high UVR) to the coral holobiont through its mycosporine-like amino acids (MAAs). The concentration of MAAs increases with stress and ROS in Symbodinium.[30] These UV-absorbing MAAs may also support light-harvesting pigments during photosynthesis, be source of nitrogen storage and for reproduction. More than half of the Symbodinium taxa contain MAAs.[31][32][33]
S. thermophilum was recently found to make up the bulk of the algal population inside the corals of the Persian Gulf. It is also present in the Gulf of Oman and the Red Sea, at a much lower concentration. Coral that hosted this species was able to tolerate the 35 °C (95 °F) waters of the Persian Gulf, much hotter than the 31 °C (88 °F) of coral reefs globally.[35]
Molecular systematics
The advent of
Phylogenetic disparity among "clades"
The earliest
Recently (2018), these distinct clades within the family of
Species diversity
The recognition of species diversity in this genus remained problematic for many decades due to the challenges of identifying morphological and biochemical traits useful for diagnosing species.
The analysis of additional phylogenetic markers show that some Symbiodinium that were initially identified by slight differences in ITS sequences may comprise members of the same species[40] whereas, in other cases, two or more genetically divergent lineages can possess the same ancestral ITS sequence.[42][43] When analysed in the context of the major species concepts,[44] the majority of ITS2 sequence data provide a reasonable proxy for species diversity.[39][40][45] Currently, ITS2 types number in the hundreds, but most communities of symbiotic cnidaria around the world still require comprehensive sampling. Furthermore, there appears to be a large number of unique species found in association with equally diverse species assemblages of soritid foraminifera,[46] as well as many other Symbiodinium that are exclusively free-living and found in varied, often benthic, habitats.[47] Given the potential species diversity of these ecologically cryptic Symbiodinium, the total species number may never be accurately assessed.[46]
Clone diversity and population genetics
Through the use of
Species diversity, ecology, and biogeography
Geographic distributions and patterns of diversity
Symbiodinium are perhaps the best group for studying micro-eukaryote physiology and ecology for several reasons. Firstly, available phylogenetic and population genetic markers allow for detailed examination of their genetic diversity over broad spatial and temporal scales. Also, large quantities of Symbiodinium cells are readily obtained through the collection of hosts that harbor them. Lastly, their association with animals provides an additional axis by which to compare and contrast ecological distributions.[citation needed]
The earliest genetic methods for assessing Symbiodinium diversity relied on low-resolution molecular markers that separated the genus into a few evolutionarily divergent lineages, referred to as "clades". Previous characterizations of geographic distribution and dominance have focused on the clade-level of genetic resolution, but more detailed assessments of diversity at the species level are needed. While members of a given clade may be ubiquitous, the species diversity within each clade is potentially large, with each species often having different ecological and geographic distributions related to their dispersal ability, host biogeography, and external environmental conditions. A small number of species occur in temperate environments where few symbiotic animals occur. As a result, these high latitude associations tend to be highly species specific.[citation needed]
Species diversity assigned to different ecological guilds
The large diversity of Symbiodinium revealed by genetic analyses is distributed non-randomly and appears to comprise several
Symbiodinium from functional groups 2, 3, and 4 are known to exist because they culture easily, however species with these life histories are difficult to study because of their low abundance in the environment.Free-living and "non-symbiotic" populations
There are few examples of documented populations of free-living Symbiodinium.
Culturing
Certain Symbiodinium strains and/or species are more easily
Culturing is a selective process, and many Symbiodinium isolates growing on artificial media are not typical of the species normally associated with a particular host. Indeed, most host–specific species have yet to be cultured. Samples for genetic analysis should be acquired from the source colony in order to match the resulting culture with the identity of the dominant and ecologically relevant symbiont originally harbored by the animal.[50][62][63]
Life cycle
The
Large tetrads are occasionally observed, particularly when cells in stationary growth phase are transferred to fresh media. However, it is unknown whether this stage is the product of two consecutive mitotic divisions, or perhaps a process that generates sexually competent motile cells (i.e. gametes), or is the end result of meiosis (i. e. as meiotic tetrads) following gamete fusion. There is no cytological evidence for sexual recombination, and meiosis has never been observed, but population genetic evidence supports the view that Symbiodinium periodically undergo events of sexual recombination. How, when, and where the sexual phase in their life history occurs remains unknown.[42][65][66]
Morphology
The morphological description of the genus Symbiodinium is originally based on the type species (holotype) S. microadriaticum.[38][67] Because these dinoflagellates possess two major stages in their life history (see above), namely the mastigote (motile) and coccoid (non-motile) stages, the morphology of both is described in order to provide a complete diagnosis of the organism.
Flagellated (mastigote) cell
The motile
The internal organelles of the mastigote are essentially the same as described in the coccoid cell (see below). The transition from mastigote to coccoid stage in Symbiodinium occurs rapidly, but details about cellular changes are unknown.
Coccoid cell
The coccoid cell of Symbiodinium is spherical and ranges in average diameter from 6 to 13 µm, depending on the species (Blank et al. 1989). This stage is often wrongly interpreted as a
Cell wall
The coccoid cell is surrounded by a
Chloroplast
Most described species possess a single, peripheral, reticulated chloroplast bounded by three membranes. The volume of the cell occupied by the chloroplast varies among species.[38] The lamellae comprise three closely appressed (stacked) thylakoids, and are attached by two stalks to the pyrenoid[38] surrounded by a starch sheath. In three of the described species, the thylakoids are in parallel arrays, but in S. pilosum, there are also peripheral lamellae. There are no thylakoid membranes invading the pyrenoid, which is unlike other symbiotic dinoflagellates.[73][74] The lipid components of thylakoids include the galactolipids as monogalactosyl-diglycerides (MGDG)[75] and digalactosyl-diglycerides( DGDG),;[76] the sulpholipid sulphoquinovosyl-diglyceride (SQDG),[77] phosphatidyl glycerol,[78] and phosphatidyl choline. Associated with these are various fatty acids.[79] The light-harvesting and reaction centre components in the thylakoid membrane include a water-soluble peridinin-chlorophyll a-protein complex (PCP or PerCP),[80] and a membrane-bound chlorophyll a-chlorophyll c2-peridinin-protein-complex (acpPC),[81] along with typical photosynthetic
All cultured isolates (i.e.
Nucleus
In general, the
Other cytoplasmic organelles
There are several additional organelles found in the cytoplasm of Symbiodinium. The most obvious of these is the structure referred to as the "accumulation body". This is a membrane-bound
Species
The following species are recognised by the World Register of Marine Species:[1]
- Symbiodinium bermudense R.K.Trench, 1993
- Symbiodinium californium A.T.Banaszak, R.Iglesias-Prieto & R.K.Trench, 1993
- Symbiodinium cariborum R.K.Trench, 1993
- Symbiodinium corculorum R.K.Trench, 1993
- Symbiodinium glynnii D.C.Wham, G.Ning, T.C.LaJeunesse, 2017 [91]
- Symbiodinium goreaui Trench & Blank, 2000
- Symbiodinium kawagutii Trench & Blank, 2000
- Symbiodinium meandrinae R.K.Trench, 1993
- Symbiodinium microadriaticum Freudenthal, 1962
- Symbiodinium minutum T.C.LaJeunesse, J.E. Parkinson & J.D.Reimer, 2012
- Symbiodinium pilosum Trench & Blank, 2000
- Symbiodinium psygmophilum LaJeunesse, T.C., Parkinson, J.E. & Reimer, J.D., 2012
- Symbiodinium pulchrorum R.K.Trench, 1993
- Symbiodinium thermophilum, new species [92]
References
- ^ a b Guiry, Michael D. (2014). "Symbiodinium Freudenthal, 1962". WoRMS. World Register of Marine Species. Retrieved 2015-01-29.
- JSTOR 1221270.
- ^ PMID 30100341.
- S2CID 43084578.
- ^ Kawaguti, Siro (1944). "On the physiology of reef corals VI. Study on the pigments". Palau Tropical Biological Station Studies. 2: 617–74.
- S2CID 85877213.
- ^ S2CID 22673808.
- S2CID 21833840.
- S2CID 27108503.
- .
- S2CID 5871917.
- S2CID 16428743.
- S2CID 19361052.
- PMID 20444713.
- S2CID 46191566.
- .
- ^ Colombo-Pallotta et al. 2010
- S2CID 3896954.
- .
- S2CID 12607336.
- PMID 16928632.
- PMID 18645181.
- S2CID 84675726.
- S2CID 1240348.
- .
- PMID 18322010.
- S2CID 19100056.
- ^ PMID 19740874.
- S2CID 30508571.
- PMID 31726795.
- PMID 33146374.
- PMID 32108224.
- PMID 29898658.
- ^ David DeFranza (2010-02-17). "Andaman Sea Coral May Hold the Secret to Warm Water Reef Survival". Treehugger. Retrieved 2015-02-02.
- ISSN 0013-0613. Retrieved 2016-04-30.
- PMID 1565660.
- PMID 21085582.
- ^ S2CID 83712799.
- ^ S2CID 24285565.
- ^ PMID 22216157.
- ^ Christian Renicke: Symbiodinium cp23S RFLP and sequence analysis, Pringle Lab, Grossman Lab, Jul 23, 2018
- ^ S2CID 32227215.
- S2CID 5890376.
- PMID 18027281.
- S2CID 12791319.
- ^ S2CID 24642825.
- ^ S2CID 10186027.
- ^ S2CID 25577087.
- ^ PMID 22082053.
- ^ S2CID 84357806.
- PMID 9230434.
- S2CID 7765487.
- ^ S2CID 36226084.
- .
- ^ PMID 18478069.
- PMID 17141602.
- S2CID 17895332.
- ^ Culturing, Georgia State University, International Genetically Engineered Machine (iGEM)
- S2CID 84190993.
- S2CID 84395179.
- S2CID 83896405.
- S2CID 2335127.
- S2CID 85919438.
- ^ JSTOR 2432757.
- S2CID 84351451.
- S2CID 4208350.
- ^ .
- ISBN 978-0-632-00915-2.
- ISBN 978-0-632-00915-2.
- ISBN 978-1-139-46987-6.[page needed]
- ^ Markell, DA; Trench, RK; Iglesias-Prieto, R (1992). "Macromolecules associated with the cell-walls of symbiotic dinoflagellates". Symbiosis. 12 (1): 19–31. INIST 5092729.
- PMID 10975645.
- ^ Trench, RK; Winsor, H (1987). "Symbiosis with dinoflagellates in two pelagic flatworms, Amphiscolops sp. and Haplodiscus sp". Symbiosis. 3 (1): 1–21. INIST 8265704.
- S2CID 84895398.
- ^ Monogalactosyl Diglyceride, biomol
- ^ Digalactosyl diglyceride, Merck Sigma-Aldrich
- ^ Sulfoquinovosyl diglyceride, Karel's Nutrition Blog
- ^ Phosphatidylglycerol and Related Lipids, The LipidWeb
- S2CID 20410939.
- PMC 4030626, PMID 24678668, PMC4030626(Web Archive July 2021, 10th)
- ^ Dariusz M. Niedzwiedzki, Jing Jiang, Cynthia S. Lo, Robert E. Blankenship: Spectroscopic properties of the Chlorophyll a–Chlorophyll c2–Peridinin-Protein-Complex (acpPC) from the coral symbiotic dinoflagellate Symbiodinium. In: Photosynthesis Research, volume 120, pp. 125–139, (May 2014)/ January 2013, 20th, doi:10.1007/s11120-013-9794-5
- S2CID 84255943.
- JSTOR 3030171.
- PMID 8721755.
- S2CID 34202181.
- .
- S2CID 84705656.
- ^ S2CID 45228641.
- S2CID 7258554.
- .
- ^ Drew C. Wham, Gang Ning, and Todd C. LaJeunesse (2017) [Symbiodinium glynnii sp. nov., a species of stress-tolerant symbiotic dinoflagellates from pocilloporid and montiporid corals in the Pacific Ocean]. Phycologia: 2017, Vol. 56, No. 4, pp. 396-409.
- ^ Algal species helps corals survive in Earth's hottest reefs
External links
- "Symbiodinium" at the Encyclopedia of Life
- An image of Symbiodinium at Smithsonian Ocean Portal