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Tetraspora is a genus of green algae in the family Tetrasporaceae of the order Chlamydomonadales, division Chlorophyta. Species of Tetraspora are unicellular green algae that exist in arrangements of four and consist of cells being packaged together in a gelatinous envelope that creates macroscopic colonies. These are primarily freshwater organisms, although there have been few cases where they have been found inhabiting marine environments and even contaminated water bodies. Tetraspora species can be found all around the globe, except in Antarctica. Despite the ubiquitous presence, the greatest growth of the genera's species is seen in the Polar climate.
Tetraspora species are non-motile and instead of having flagella, they possess pairs of pseudoflagella which are part of the Pseudociliate. On average the cell diameter of Tetraspora ranges from 6-13 μm. Energy is accumulated via photosynthesis through two cup-shaped chloroplasts, making the species . Blooms have been noted in contaminated environments due to excess augmentation of ammonia from industrial waste and are now being associated with the drop in biodiversity in such water bodies.
Both sexual and asexual reproduction are possible for species within this genus. In addition, mitosis is well-defined in Tetraspora species; particularly investigated in T. gelatinosa. Cell division involves the elaborate arrangement of , basal body complexes and involve the use of structures like and protoplast.
Studies have shown the antimicrobial properties of certain species. In addition, Tetraspora is an important photobiological hydrogen producer and therefore is intensively being looked at for biofuel purposes. , thirty species have been classified into this genus.
Tetraspora species are found on every continent, with the exception of Antarctica, and can be located at all latitudes. Therefore, they are found in all climatic zones: polar, tropics, warm and cool temperate zones and the equatorial zones. While they can be present in all climatic zones, the most optimal zones are cool temperate and the polar zones. This is because of the species preferring cold water to warm.
In water bodies associated with sewage waste, industrial waste and fishery waste, Tetraspora blooms have been documented. Spewing of sewage, industrial and fishery wastes leads to anthropogenic eutrophication, where there is excess augmentation of ammonia; a principal nitrogen source for certain species of Tetraspora. The excess nitrogen is proposed to contribute to uncontrolled cell proliferation of Tetraspora colonies; resulting in algal blooms. Tetraspora blooms have negative effects on the overall environmental ecology because they shift and alter the chemical properties of the water. This is because with the mass growth, hypoxia and/or anoxia can occur and these may have detrimental effects on biodiversity and survivability of other organisms such as fish. (2025). 9781402084799 ISBN 9781402084799
The size of cells has been found to vary based on the type of Tetraspora species and the type of climatic zone the species is found in. On average the diameter of species in the genus Tetraspora ranges from 6-13 μm, with the species in the tropics usually being the smallest (6-9 μm), followed by the temperate zone species (6-14 μm), and the polar species (7.5-13 μm). The difference in cell size therefore also impacts sizes of the colonies, but sizes of colonies also vary with whether the cells are residing in stagnant or flowing water. In stagnant water, colonies may range from 5–10 cm in length, while in flowing water, colonies may reach lengths up to 50 cm. In addition to impacting colony size, the type of water (stagnant or free flowing) also impacts the morphology of the colonies. Most macroscopic colonies of Tetraspora are cylindrical in nature, but in stagnant water colonies may appear as short sacs and clubs with Thallus that resemble balloons. Flowing water colonies on the other hand, tend to form narrow cylindrical structures with the thalli also being more or less cylindrical and sometimes can be lightly rounded at the sheaths.
Tetraspora species do not possess a flagellum of the 9+2 microtubular fibre configuration, instead they have pseudoflagellum with a 9+0 fibre confirmation; where the central two tubular fibres are absent. There are two pseduoflagelulla that exist in a pair and both protrude from the anterior region of the cell and into the gelatinous matrix. Additionally, it has been found that the pseudoflagella are longer than the actual cells. The pseudoflagella is part of the pseudociliary apparatus, which consists of a cytoplasmic microtubule system, striated fibre system, basal bodies, and the pseudoflagella themselves. Pseudoflagella each display a striped pattern, where they are seen to regularly have striped structures of light and dark sections of equal length. On average, the length of pseudoflagella is from 70 to 120 μm long and 0.70-1.60 μm wide, but they can get up to 155 μm in length.
When living conditions become less favourable, many species of the genus Tetraspora also have the ability to form into hypanospores called Akinete. Akineties are thick-walled spores that are brown in colour with a diameter of 12.9-15.80 μm and a cell wall thickness of 0.6-1.10 μm. They function as resting cells which are resistant to cold temperatures and desiccation. The process of division of mature akineties is done by amoeboid protoplasts located inside the mucilaginous envelopes.
Cell division in Tetraspora species has been described. It is noted that prior to mitosis beginning, cells become immotile and the basal bodies located at the surface of cells start to retreat in. This causes the preprophase nucleus to migrate toward retreating basal body complex, around which microtubules start to gather. The basal body complex arranges itself to be closely associated with one pole of the cell, creating a mitotic spindle known as open polar fenestrae. Furthermore, it is speculated that the spindle itself may also be unicentric. Eventually, microtubules extend from the spindle, and during anaphase, they penetrate through the and split the nucleus. Subsequently, to telophase, the nucleus reforms, but a phycoplast forms. In addition, a protoplast is found inside the cell wall and is noted to rotate within the wall during cleavage; a process known to occur by the cell undergoing furrowing.
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