Tetraselmis

Last updated

Tetraselmis
Bacillario008.png
Tetraselmis suecica
Scientific classification OOjs UI icon edit-ltr.svg
(unranked): Viridiplantae
Division: Chlorophyta
Class: Chlorodendrophyceae
Order: Chlorodendrales
Family: Chlorodendraceae
Genus: Tetraselmis
F.Stein, 1878
Species

See text

Tetraselmis is a genus of phytoplankton. Tetraselmis is a green algal genus within the order Chlorodendrales, and they are characterized by their intensely-colored green chloroplast, their flagellated cell bodies, the presence of a pyrenoid within the chloroplast, and a scale-produced thecal-wall. [1] [2] Species within this genus are found in both marine and freshwater ecosystems across the globe; their habitat range is mainly limited by water depth due to their photosynthetic nature. [1] Thus, they live in diverse water environments if enough nutrients and light are available for net photosynthetic activity. Tetraselmis species have proven to be useful for both research and industry. Tetraselmis species have been studied for understanding plankton growth rates, and recently a colonial species is being used to gain an understanding of multicellularity evolution. [1] [3] Additionally, many species are currently being examined for their use as biofuels due to their high lipid content. [4]

Contents

History

The genus name was first presented to the scientific community in Germany in 1878 by F. von Stein. [5] The genus Tetraselmis has undergone many taxonomic changes over the years, largely due to more advanced research techniques that have aided scientists in their classification. Many botanists have further contributed to the knowledge surrounding Tetraselmis, and have discovered many species within the genera. Some notable contributors include R.W. Butcher, T. Hori, R.E. Norris, and M. Chihara.

Location and ecology

Tetraselmis species are found in both marine and freshwater ecosystems, and they occupy niches as primary producers in benthic and planktonic food webs. [1] They can be found in many global waters, and their main enforcer of habitat range is light availability which restricts cells to the photic zone of the water column. The primary producers of aquatic ecosystems are mostly unicellular photosynthetic plankton, which includes Tetraselmis. Planktonic photoautotrophs are important components of aquatic food webs because they form the first trophic level. Most Tetraselmis species are free-living, however, some species are symbionts within animals. [1] Marine species often populate rapidly and densely, causing plankton blooms in shoreline and bay areas. [1] Tetraselmis is a specifically important genus for studying and understanding plankton growth rate dynamics. [1]

Cell morphology

Tetraselmis species vary greatly in cell size and shape. Cells can be round, ovoid, elliptical, flattened, compressed, or a combination of these shapes, in which their side lengths can vary in range from 3.5-25 µm. [6] Tetraselmis cells have four flagella of equal length, which emerge from a depression near the apex. [1] In most species, the flagella emerge in pairs and project away from each other. [1] Generally, individual cells travel in a linear fashion for a long period of time, and then rapidly change direction without stopping, in which their flagella generate force for motion through an aqueous environment. [1] See figure 1 for general features of the flagella and cell body of Tetraselmis species.

They have a single large chloroplast, usually with four anterior lobes, which occupies most of the cytoplasmic compartment. [7] Some species have reduced or no lobes, and some have developed posterior lobes. [1] Like other green algal lineages, the thylakoids and lamellae have no set number or pattern within the chloroplast. [1] The chloroplast contains one pyrenoid, which is encircled in a starch-shell, and one eyespot. [1] The pyrenoid is usually central within the cell; the location of the stigma however, varies from species largely due to cell size and shape. [1] The stigma is composed of two lipid-granule layers separated by a single thylakoid, which are parallel with the chloroplast membrane. [1] Stigmas are a concentration of pigment granules which the cell uses to detect light allowing them to orientate themselves within the water column. [1] Both the pyrenoid and the stigma can be used for taxonomic classification due to their reliable and inherent positioning in species. [1] See figure 1 for a visual representation of the position of the chloroplast, stigma, pyrenoid, and flagellar depression.

The nucleus of the cell lies between the anterior lobes of the chloroplast in parallel with the pyrenoid, and some species have developed anterior nuclear lobes. [1] The nucleus is centrally located and is parallel with the flagellar depression and pyrenoid. [1] Additionally, condensed chromatin can be viewed in the nucleus of certain species. [1] See figure 1 for nuclear positioning within cells. The Golgi of Tetraselmis species has a distinct number of Golgi bodies usually within the range of 2-4, but species can have up to 8 or more. [1] This is a reliable characteristic that is used to help classify species. [1] Golgi bodies lie between the chloroplast and the basal bodies; cis-Golgi face the chloroplast and trans-Golgi face the basal bodies. Mitochondria are dispersed throughout the cytoplasm in no pattern. [1] The cytoplasm may contain additional organelles and macromolecules such as lipid droplets, vacuoles, and lysosomes. [1] Additionally, the starch produced by Tetraselmis is the same as those produced from land plants.

The theca of most species closely encloses the cell body, but can become separated due to irregularities in cell shape. [1] Theca are usually smooth, but some species have developed distinct creases that cross perpendicularly near the cell apex, giving the cell the appearance of being divided into four longitudinal sections. [1] Some species also have a twisted cell posterior that is mirrored in the thecal wall produced. [1] The only perforation of the theca is where the flagella emerge, which is termed the apical depression. [1] The pore is a long slit with thecal extensions that border it, extending upwards to protect the flagella base. [1] In cells that have lost their flagella the thecal extensions grow to cover the slit, but they do not fuse; non-motile cells of Tetraselmis have flagellar stubs that remain within the thecal compartment. [1] Additionally, many species have thick curly hairs anchored to the cell wall near the flagellar base. [1] The hairs are cross striated and have a spiral pattern, which is similar to flagellar hairs, but they are thicker and longer than flagellar hairs. [1] Scale production begins during prophase, and the scales are brought to the cell membrane promptly after completion of cytokinesis and the two daughter cells are separated. [2] Fusion of the scales happens externally and begins near the posterior end, extending forwards to the anterior end in which the flagellar slit forms last. [1]

Each cell has four flagella of equal length, in which the flagella are shorter than the length of the cell. [1] The flagella emerge from the apical depression in pairs and point in opposite directions, running parallel to the long side of the cell. [1] Due to their emergence from a deep depression, the mechanical force the flagella can produce is restricted. [1] Other lineages with non-depressed flagellar insertions can produce higher amounts of flagellar force, because the flagellar base is not geometrically limited. [1] The flagella of Tetraselmis species are thick, covered in mucilaginous material, and have a blunt end. [1] They are also covered in flagellar hairs which are loosely attached to the cell exterior; they are cross-striated with two scale layers on flagella. [1] See figure 3 for a detailed picture of flagella including their scales and hair. The inner layer is compact and densely covers the flagella, and hair cells are attached to the cell membrane through small sections of membrane that are not covered due to patterning. [1] The outer scale layer is made of small-round scales which are mainly used to overlap bare membrane not covered by the inner scales. [1] The inner scales are larger than the outer scales, and usually resemble a pentagon or square in shape. [1] See figure 1 for a generalized drawing of flagellar scales. The flagellar hairs have a distinct sequence of structural components, the proximal filament connects the flagellum and cell surface, this is followed by the tubular shaft, then the transition zone in which the shaft is modified, followed by a stretch of linear globular subunits, and the hair ends with a distal filament. [1] The distal filament and transition zone are the only components that are not produced by certain species. [1] Flagellar hairs have a fixed number of distal subunit repeats, which varies between 2-44 subunits depending on the species. [1] Thus, flagellar hairs are a good morphological tool for species comparison and classification. [1] Figure 1 includes these hairs on the flagella drawing. Species use their flagella to travel in straight lines while rotating along their axis, in which they travel in one direction for long distances and then abruptly change directions instantaneously without stopping. [1] Some species differ from this pattern of movement and move in less rigid and structured fashion. [1]

Life-stages

Tetraselmis species have three life stages which includes a flagellated stage, a vegetative non-motile stage, and a cyst stage. [7] The vegetative non-motile stage is the dominant life-stage of most species. [1] The only structural difference between the flagellated and vegetative stage is the number of scale layers in the thecal-wall; the flagellated stage only ever has one layer, while the vegetative state has two or more. [1] Cells in the cyst stage lose their flagella, and are termed as being aflagellate, and they produce a thick thecal-shell for protection. [1] During any of the life stages it is possible for Tetraselmis species to undergo a complete transformation and develop flagella, becoming motile.

Tetraselmis species undergo cell division during the non-motile stage, producing two daughter cells, and most species only undergo one division cycle. [1] During cell division, organelles divide synchronously before nuclear division. [1] Cell division is aided by a phycoplast, which is a microtubule structure that helps the cell divide the nuclei into each daughter cell. [1] Daughter cells can develop into flagellated cells or remain non-motile, depending on environmental conditions. [1] Additionally, vegetative cells whether flagellate or immotile are anchored to the thecal wall by four microtubule contact points. [1]

Practical importance

Tetraselmis species have been important for cellular biology research, for studying plankton growth cycles, and they may have future use in biofuel production. For example, the species T. indica is being used to study how asymmetric cell-division during mitosis results in clonal cell heterogeneity. [3] This species forms a clonal colony in which the cells are morphologically and ultrastructurally different, and many cells specialize and develop independent physical properties. [3] The asymmetric division of daughter cells results in the unequal division of both cytoplasm and nucleoplasm. [3] Scientists believe this phenomenon allows clones to form “sub-populations” that remain close to one another, in which the cells cooperate with one another and act as one large population. [3] Asymmetric cell division clearly plays an important role in the production of phenotypically diverse cells in multicellular systems, and this has important implications for multicellular organisms, humans included. [3]

Tetraselmis and other microalgae species are used as food in aquaculture, and for biotechnology uses. [4] Tetraselmis species, along with other microalgae are a promising source for biofuel use due to their fast growth rate, high lipid content, cheaper photosynthetic mechanisms, less need for agricultural land, useful by-products, and for being environmentally friendly. Research is currently being performed into specific microalgae species for biofuel use. [4] 'Tetraselmis has a very high lipid level; their amino acids stimulate feeding in marine organisms.[ citation needed ]

T. suecica EPS have antioxidant activity and cytotoxic effects on tumor cells; therefore, they could offer greater advantages as possible natural nutraceuticals for the pharmaceutical industry. [8]

Additional information

Tetraselmis is green, motile, and usually grows 10 µm long x 14 µm wide. The species T. convolutae is a symbiont of the acoelomate animal Symsagittifera roscoffensis (and can also live freely in the ocean). [9]

Species

Related Research Articles

<span class="mw-page-title-main">Chlorophyceae</span> Class of green algae

The Chlorophyceae are one of the classes of green algae, distinguished mainly on the basis of ultrastructural morphology. They are usually green due to the dominance of pigments chlorophyll a and chlorophyll b. The chloroplast may be discoid, plate-like, reticulate, cup-shaped, spiral- or ribbon-shaped in different species. Most of the members have one or more storage bodies called pyrenoids located in the chloroplast. Pyrenoids contain protein besides starch. Some green algae may store food in the form of oil droplets. They usually have a cell wall made up of an inner layer of cellulose and outer layer of pectose.

<span class="mw-page-title-main">Flagellum</span> Cellular appendage functioning as locomotive or sensory organelle

A flagellum is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are known as flagellates.

<i>Euglena</i> Genus of unicellular flagellate eukaryotes

Euglena is a genus of single cell flagellate eukaryotes. It is the best known and most widely studied member of the class Euglenoidea, a diverse group containing some 54 genera and at least 200 species. Species of Euglena are found in fresh water and salt water. They are often abundant in quiet inland waters where they may bloom in numbers sufficient to color the surface of ponds and ditches green (E. viridis) or red (E. sanguinea).

<i>Chlamydomonas</i> Genus of algae

Chlamydomonas is a genus of green algae consisting of about 150 species of unicellular flagellates, found in stagnant water and on damp soil, in freshwater, seawater, and even in snow as "snow algae". Chlamydomonas is used as a model organism for molecular biology, especially studies of flagellar motility and chloroplast dynamics, biogenesis, and genetics. One of the many striking features of Chlamydomonas is that it contains ion channels (channelrhodopsins) that are directly activated by light. Some regulatory systems of Chlamydomonas are more complex than their homologs in Gymnosperms, with evolutionarily related regulatory proteins being larger and containing additional domains.

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

The eyespot apparatus is a photoreceptive organelle found in the flagellate or (motile) cells of green algae and other unicellular photosynthetic organisms such as euglenids. It allows the cells to sense light direction and intensity and respond to it, prompting the organism to either swim towards the light, or away from it. A related response occurs when cells are briefly exposed to high light intensity, causing the cell to stop, briefly swim backwards, then change swimming direction. Eyespot-mediated light perception helps the cells in finding an environment with optimal light conditions for photosynthesis. Eyespots are the simplest and most common "eyes" found in nature, composed of photoreceptors and areas of bright orange-red red pigment granules. Signals relayed from the eyespot photoreceptors result in alteration of the beating pattern of the flagella, generating a phototactic response.

<span class="mw-page-title-main">Chlorodendrales</span> Order of algae

Chlorodendrales are an order of green, flagellated, thecate, unicellular eukaryotes, within the green algae class Chlorodendrophyceae. Prasinophyceae are defined by their cellular scales which are composed of carbohydrates, and Chlorodendrales are unique within this group due to these scales forming a fused thecal wall. Cells of Chlorodendrales are completely covered in scales, which fuse around the cell body producing the theca, but remain individually separated on the flagella, of which there are typically four per cell. Species within Chlorodendrales live in both marine and fresh water habitats, occupying both benthic and planktonic food webs. Additionally, they are photoautotrophs, meaning they produce their own food through the conversion of sunlight into chemical energy.

<i>Dunaliella</i> Genus of algae

Dunaliella is a single-celled, photosynthetic green alga, that is characteristic for its ability to outcompete other organisms and thrive in hypersaline environments. It is mostly a marine organism, though there are a few freshwater species that tend to be more rare. It is a genus in which certain species can accumulate relatively large amounts of β-carotenoids and glycerol in very harsh growth conditions consisting of high light intensities, high salt concentrations, and limited oxygen and nitrogen levels, yet is still very abundant in lakes and lagoons all around the world.

<i>Nephroselmis</i> Genus of algae

Nephroselmis is a genus of green algae. It has been placed in the family Nephroselmidaceae, although a 2009 study suggests that it should be separated into its own class, Nephroselmidophyceae. One species can be an endosymbiont of Hatena arenicola.

<i>Stephanosphaera</i> Genus of algae

Stephanosphaera is a genus of green algae in the family Haematococcaceae, containing the single species Stephanosphaera pluvialis. It forms colonies of flagellated cells. Although it was once placed in the family Volvocaceae, it is not closely related to them; its sister is the unicellular genus Balticola.

<i>Trebouxia</i> Genus of algae

Trebouxia is a unicellular green alga. It is a photosynthetic organism that can exist in almost all habitats found in polar, tropical, and temperate regions. It can either exist in a symbiotic relationship with fungi in the form of lichen or it can survive independently as a free-living organism alone or in colonies. Trebouxia is the most common photobiont in extant lichens. It is a primary producer of marine, freshwater and terrestrial ecosystems. It uses carotenoids and chlorophyll a and b to harvest energy from the sun and provide nutrients to various animals and insects.

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

Rhodomonas is a genus of cryptomonads. It is characterized by its red colour, the square-shaped plates of its inner periplast, its short furrow ending in a gullet, and a distinctly shaped chloroplast closely associated with its nucleomorph. Historically, Rhodomonas was characterized by its red chloroplast alone, but this no longer occurs as its taxonomy has become increasingly based on molecular and cellular data. Currently, there is some debate about the taxonomic validity of Rhodomonas as a genus and further research is needed to verify its taxonomic status. Rhodomonas is typically found in marine environments, although freshwater reports exist. It is commonly used as a live feed for various aquaculture species.

Geminigera /ˌdʒɛmɪnɪˈdʒɛɹə/ is a genus of cryptophyte from the family Geminigeraceae. Named for its unique pyrenoids, Geminigera is a genus with a single mixotrophic species. It was discovered in 1968 and is known for living in very cold temperatures such as under the Antarctic ice. While originally considered to be part of the genus Cryptomonas, the genus Geminigera was officially described in 1991 by D. R. A. Hill.

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

Hemiselmis is a genus of cryptomonads.

Polarella is a dinoflagellate, and is the only extant genus of the Suessiaceae family. The genus was described in 1999 by Marina Montresor, Gabriele Procaccini, and Diane K. Stoecker, and contains only one species, Polarella glacialis. Polarella inhabits channels within ice formations in both the Arctic and Antarctic polar regions, where it plays an important role as a primary producer. Polarella is a thecate dinoflagellate, wherein the cell has an outer covering of cellulose plates, which are arranged in nine latitudinal series. The general morphology of Polarella is similar to that of a typical dinoflagellate. and Polarella has a zygotic life history, wherein it alternates between a motile vegetative phase and a non-motile spiny cyst. While it is thought that the cysts of Polarella have lost their ability to form fossils, the cyst life cycle stage has acted as link to extinct members of the Suessiaceae family.

<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>Scytothamnus australis</i> Species of alga

Scytothamnus australis is a brown alga species in the genus Scytothamnus found in New Zealand. It is a sulphated polysaccharide and the type species in the genus.

<i>Gonyostomum semen</i> Species of alga

Gonyostomum semen is a species of freshwater algae in the genus Gonyostomum, with worldwide distribution. They cause nuisance algal blooms and are known to cause allergic reactions to people swimming in lakes.

Rhynchopus is a genus of flagellate excavates in the class Diplonemea. They usually have flagella of different lengths and a single subapical opening with the flagellar pocket openings and adjacent feeding apparatus merging into one. When food is scarce, mobile flagellated cells are produced, suggesting the presence of a fully flagellated and dispersive phase in the life cycle, serving to distinguish Rhynchopus from Diplonema. Most species are free-living, others are symbionts and R. coscinodiscivorus is an intracellular parasite of diatoms.

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

Mallomonas is a genus comprising unicellular algal eukaryotes and characterized by their intricate cell coverings made of silica scales and bristles. The group was first named and classified by Dr. Maximilian Perty in 1852. These organisms live in freshwater and are widely distributed around the world. Some well known species include Mallomonas caudata and Mallomonas splendens.

Blastodinium is a diverse genus of dinoflagellates and important parasites of planktonic copepods. They exist in either a parasitic stage, a trophont stage, and a dinospore stage. Although morphologically and functionally diverse, as parasites they live exclusively in the intestinal tract of copeods.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 Norris, R.E., Hori, T., and Chihara, M. 1980: Revision of the Genus Tetraselmis (Class Prasinophyceae). Bot. Mag. Tokyo. 93: 317-339. 10.1007/BF02488737
  2. 1 2 Becker, B., Marin, B. and Melkonian, M. 1994: Structure, composition, and biogenesis of prasinophyte cell coverings. Protoplasma. 181: 233-244. 10.1007/BF01666398
  3. 1 2 3 4 5 6 Arora, M., Anil, A.C., Burgess, K., Delany, J. and Mesbahi, E. 2015: Asymmetric cell division and its role in cell fate determination in the green alga Tetraselmis indica. J. Biosci. 40: 921-927. 10.1007/s12038-015-9576-7
  4. 1 2 3 Alonso, M., Lago, F.C., Vieites, J.M. and Espiñeira, M. 2012: Molecular characterization of microalgae used in aquaculture with biotechnology potential. Aquacult. Inter. 20: 847-857. 10.1007/s10499-012-9506-8
  5. ↑ Stein, F. von (1878). Der Organismus der Infusionsthiere nach eigenen Forschungen in systematischer Reihenfolge bearbeitet III. Abtheilung. Die Naturgeschicnte der Flagellaten oder Geisselinfusorien. Mit 24 Küpfertaflen. I. Halfte, den noch nicht abgeschlossenen allgemeinen Theil nebst Erklärung der Sämmtlichen Abbildungen enthaltend. pp. 1-154, pls I-XXIV. Leipzig: Verlag von Wilhelm Engelmann.
  6. ↑ Arora, M., Anil, A.C., Leliaert, F., Delany, J. and Mesbahi, E. 2013: Tetraselmis indica (Chlorodendrophyceae, Chlorophyta), a new species isolated from salt pans in Goa, India. European Journal of Phycology. 48: 61-78. 10.1080/09670262.2013.768357
  7. 1 2 Norris, R.E., Hori, T., and Chihara, M. 1980: Revision of the Genus Tetraselmis (Class Prasinophyceae). Bot. Mag. Tokyo. 93: 317-339. 10.1007/BF02488737
  8. ↑ Parra-Riofrío, Geovanna; García-Márquez, Jorge; Casas-Arrojo, Virginia; Uribe-Tapia, Eduardo; Abdala-Díaz, Roberto Teófilo (2020). "Antioxidant and Cytotoxic Effects on Tumor Cells of Exopolysaccharides from Tetraselmis suecica (Kylin) Butcher Grown Under Autotrophic and Heterotrophic Conditions". Marine Drugs. 18 (11): 534. doi: 10.3390/md18110534 . PMC   7693365 . PMID   33114784. CC-BY icon.svg Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License.
  9. ↑ Semmler, H; Bailly, X; Wanninger, A (Sep 2008), "Myogenesis in the basal bilaterian Symsagittifera roscoffensis (Acoela)", Frontiers in Zoology, 5: 14, doi: 10.1186/1742-9994-5-14 , PMC   2562460 , PMID   18803837
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.