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Thalassiosira pseudonana
A Thalassiosira pseudonana oogonium (egg cell) beginning to expand through the cell wall. Artificial coloring denotes chlorophyll (blue) and DNA (red).
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Clade: Stramenopiles
Phylum: Gyrista
Subphylum: Ochrophytina
Class: Bacillariophyceae
Order: Thalassiosirales
Family: Thalassiosiraceae
Genus: Thalassiosira
Species:
T. pseudonana
Binomial name
Thalassiosira pseudonana
Hasle & Heimdal, 1970

Thalassiosira pseudonana is a species of marine centric diatoms. It was chosen as the first eukaryotic marine phytoplankton for whole genome sequencing.[1] T. pseudonana was selected for this study because it is a model for diatom physiology studies, belongs to a genus widely distributed throughout the world's oceans, and has a relatively small genome at 34 mega base pairs. Scientists are researching on diatom light absorption, using the marine diatom of Thalassiosira. The diatom requires a high enough concentration of CO2 in order to utilize C4 metabolism (Clement et al. 2015).[2]

The clone of T. pseudonana that was sequenced is CCMP 1335 and is available from the National Center for Marine Algae and Microbiota at Bigelow Laboratory for Ocean Sciences. This clone was originally collected in 1958 from Moriches Bay (Long Island, New York) and has been maintained continuously in culture.

Morphology[edit]

Left: Scanning electron microscope image of the T. pseudonana. Right: False coloring of the biosilica structure of T. pseudonana to highlight its valve region, fultoportulae and girdle band region.[3]

Thalassiosira pseudonana has a radial symmetry. Its biosilica cell wall is divided into two halves, which are joined together by girdle bands, giving them a cylindrical shape or making them appear as a Petri dish.[4] The diameter of their valves ranges from 2 to 9 μm.[5][6] The valve is made up of silica ribs that radiate from the center with many 18 nm diameter nanopores between them.[7] The face of the valve has 0-1 central fultoportula and a marginal ring of fultoportulae (6-12).[8] The external openings of the central fultoportula appear as rimmed holes, whereas those of the marginal fultoportulae appear as short rimmed tubes, which are sometimes obliquely sectioned at the opening. On the internal face of the valve, two satellite pores surround the central fultoportula, while the marginal fultoportulae are surrounded by three satellite pores.[8] The rimoportula is a rimmed pore located on the valve face, with a size similar to the fultoportula, and positioned between two fultoportulae. The pervalvar axis of T. pseudonana can be either shorter than or equal to the valve diameter.[8] Their cell walls have been reported to mostly have low degree of silicification; however, their rims and ribs are highly silicified.[5][6][8] This probably enables them to have high strength while being light and using silica economically.[7][9]

Biomineralization[edit]

The distinct nano- to micro-scale structure of T. pseudonana follows a specific mechanism of formation. It begins with the formation of a thin base layer that outlines the valve.[7] Next, there is radiation of the silica ribs and the buildup of the rims, while portulae develop. The formation of the radial structure starts from a central location and spreads out in x and y axes planes.[7] During maturation, the valve surface becomes increasingly silicified, and the rim continues to develop, while the central portion of the valve becomes more rigid. Initially, the valve nanopores have irregular shapes, but they become circular during maturation.[7] The nanoscale structures of T. pseudonana are genetically mediated. The silicification process involves three categories of molecules: silaffins, which are highly post-translationally modified phosphoproteins; long chain polyamines (LCPAs); and silacidins, which are acidic proteins.[4] During valve synthesis, mRNA levels for silaffin 3 increase and lead to the formation of the base layer.[7] The presence of lower concentrations of silaffin 3 or the light form of silaffin 1 and 2 leads to the generation of spherical silica structures, indicating possible mechanisms involved in the formation of spherical silica in the ridges.[7] Over 150 genes have been identified as playing a role in the silicon biomineralization of T. pseudonana. A set of 75 genes were upregulated only during silicon limitation, while 84 genes were upregulated by both silicon and iron limitations, indicating a linkage between their iron and silicon pathways.[4][10] T. pseudonana also possesses chitin-based scaffolds that are important in the formation of their biosilica structure.[11]

Symbiosis[edit]

Thalassiosira pseudonana and the heterotrophic alphaproteobacterium Ruegeria pomeroyi form a chemical symbiosis in coculture. The bacteria provide vitamin B12 to the diatoms, which in exchange provide organic nutrients to the bacteria. In the presence of the diatom, the bacteria start producing a transporter for dihydroxypropanesulfonate (DHPS), a nutrient produced by the diatom for the bacteria.[12] A metabolic survey of the association between the bacterium Dinoroseobacter shibae and T. pseudonana showed that the bacterium has minimal impact on the growth of T. pseudonana, but it causes metabolic changes by upregulating the intracellular amino acids and amino acid derivatives of the diatom.[13] It has been demonstrated that under conditions of environmental instability and extreme warming, biofilm formation can accelerate the evolutionary responses of T. pseudonana.[14]

References[edit]

  1. ^ Armbrust, E.; Berges, J.; Bowler, C.; Green, B.; Martinez, D.; Putnam, N.; Zhou, S.; Allen, A.; Apt, K.; Bechner, M.; Brzezinski, M. A.; Chaal, B. K.; Chiovitti, A.; Davis, A. K.; Demarest, M. S.; Detter, J. C.; Glavina, T.; Goodstein, D.; Hadi, M. Z.; Hellsten, U.; Hildebrand, M.; Jenkins, B. D.; Jurka, J.; Kapitonov, V. V.; Kröger, N.; Lau, W. W.; Lane, T. W.; Larimer, F. W.; Lippmeier, J. C.; Lucas, S. (2004). "The genome of the diatom Thalassiosira pseudonana: ecology, evolution, and metabolism". Science. 306 (5693): 79–86. Bibcode:2004Sci...306...79A. CiteSeerX 10.1.1.690.4884. doi:10.1126/science.1101156. PMID 15459382. S2CID 8593895.
  2. ^ Clement, R., Dimnet, L., Maberly, S. C., Gontero, B. 2015. The nature of the CO2‐concentrating mechanisms in a marine diatom, Thalassiosira pseudonana. New Phytologist Trust 209: 1417–1427.
  3. ^ Gröger, Philip; Poulsen, Nicole; Klemm, Jennifer; Kröger, Nils; Schlierf, Michael (9 November 2016). "Establishing super-resolution imaging for proteins in diatom biosilica". Scientific Reports. 6 (1): 36824. Bibcode:2016NatSR...636824G. doi:10.1038/srep36824. ISSN 2045-2322. PMC 5101815. PMID 27827427.
  4. ^ a b c Armbrust, E. Virginia (May 2009). "The life of diatoms in the world's oceans". Nature. 459 (7244): 185–192. Bibcode:2009Natur.459..185A. doi:10.1038/nature08057. ISSN 1476-4687. PMID 19444204. S2CID 3738371.
  5. ^ a b Hasle, G. R.; Heimdal, B. R. (1 April 1970). "Some Species of the Centric Diatom Genus Thalassiosira Studied in the Light and Electron Microscopes". Nova Hedwigia, Beihefte. 31: 543–581. doi:10.1127/nova.beihefte/31/1970/543. S2CID 85688848.
  6. ^ a b Rad Menendez, Cecilia (2011). Phenotypic and genotypic characterization of Thalassiosira pseudonana (Bacillariophyceae) strains (Ph.D. thesis). University of Aberdeen.
  7. ^ a b c d e f g Hildebrand, Mark; York, Evelyn; Kelz, Jessica I.; Davis, Aubrey K.; Frigeri, Luciano G.; Allison, David P.; Doktycz, Mitchel J. (October 2006). "Nanoscale control of silica morphology and three-dimensional structure during diatom cell wall formation". Journal of Materials Research. 21 (10): 2689–2698. Bibcode:2006JMatR..21.2689H. doi:10.1557/jmr.2006.0333. ISSN 2044-5326. S2CID 138652614.
  8. ^ a b c d Hevia-Orube, Joana; Orive, Emma; David, Helena; Díez, Alejandro; Laza-Martínez, Aitor; Miguel, Irati; Seoane, Sergio (2 January 2016). "Molecular and morphological analyses of solitary forms of brackish Thalassiosiroid diatoms (Coscinodiscophyceae), with emphasis on their phenotypic plasticity". European Journal of Phycology. 51 (1): 11–30. doi:10.1080/09670262.2015.1077394. ISSN 0967-0262.
  9. ^ Hamm, Christian E.; Merkel, Rudolf; Springer, Olaf; Jurkojc, Piotr; Maier, Christian; Prechtel, Kathrin; Smetacek, Victor (February 2003). "Architecture and material properties of diatom shells provide effective mechanical protection". Nature. 421 (6925): 841–843. Bibcode:2003Natur.421..841H. doi:10.1038/nature01416. ISSN 1476-4687. PMID 12594512. S2CID 4336989.
  10. ^ Mock, T., Samanta, M. P., Iverson, V., Berthiaume, C., Robison, M., Holtermann, K., ... & Armbrust, E. V. (5 February 2008). "Whole-genome expression profiling of the marine diatom Thalassiosira pseudonana identifies genes involved in silicon bioprocesses". PNAS. 105 (5): 1579–1584. doi:10.1073/pnas.0707946105. PMC 2234187. PMID 18212125.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ Brunner, Eike; Gröger, Christian; Lutz, Katharina; Richthammer, Patrick; Spinde, Katrin; Sumper, Manfred (1 September 2009). "Analytical studies of silica biomineralization: towards an understanding of silica processing by diatoms". Applied Microbiology and Biotechnology. 84 (4): 607–616. doi:10.1007/s00253-009-2140-3. ISSN 1432-0614. PMID 19629468. S2CID 23179914.
  12. ^ Kujawinski, Elizabeth B.; et al. (2016). "The Ocean Microbiome: Metabolic Engine of the Marine Carbon Cycle". Microbe Magazine. 11 (6): 262–267. doi:10.1128/microbe.11.262.1.
  13. ^ Paul, Carsten; Mausz, Michaela A.; Pohnert, Georg (1 April 2013). "A co-culturing/metabolomics approach to investigate chemically mediated interactions of planktonic organisms reveals influence of bacteria on diatom metabolism". Metabolomics. 9 (2): 349–359. doi:10.1007/s11306-012-0453-1. ISSN 1573-3890. S2CID 255127394.
  14. ^ Schaum, C.‐E. (March 2019). "Enhanced biofilm formation aids adaptation to extreme warming and environmental instability in the diatom Thalassiosira pseudonana and its associated bacteria". Limnology and Oceanography. 64 (2): 441–460. Bibcode:2019LimOc..64..441S. doi:10.1002/lno.11050. ISSN 0024-3590. S2CID 92224508.

Further reading[edit]

Meksiarun, Phiranuphon; Spegazzini, Nicolas; Matsui, Hiroaki; Nakajima, Kensuke; Matsuda, Yusuke; Sato, Hidetoshi (January 2015). "In Vivo Study of Lipid Accumulation in the Microalgae Marine Diatom Thalassiosira pseudonana Using Raman Spectroscopy". Applied Spectroscopy. 69 (1): 45–51. Bibcode:2015ApSpe..69...45M. doi:10.1366/14-07598. PMID 25506782. S2CID 40963425.

Yi, Andy Xianliang; Leung, Priscilla T. Y.; Leung, Kenneth M. Y. (September 2014). "Photosynthetic and molecular responses of the marine diatom Thalassiosira pseudonana to triphenyltin exposure". Aquatic Toxicology. 154: 48–57. doi:10.1016/j.aquatox.2014.05.004. PMID 24858899.

Luo, Chun-Shan; Liang, Jun-Rong; Lin, Qun; Li, Caixia; Bowler, Chris; Anderson, Donald; Wang, Peng; Wang, Xin-Wei; Gao, Ya-Hui (December 2014). "Cellular Responses Associated with ROS Production and Cell Fate Decision in Early Stress Response to Iron Limitation in the Diatom Thalassiosira pseudonana". Journal of Proteome Research. 13 (12): 5510–5523. doi:10.1021/pr5004664. PMC 4261981. PMID 25372880.

Sunda, William G.; Shertzer, Kyle W.; Coggins, Lew (October 2014). "Positive feedbacks between bottom-up and top-down controls promote the formation and toxicity of ecosystem disruptive algal blooms: A modeling study". Harmful Algae. 39: 342–356. doi:10.1016/j.hal.2014.09.005.

Samukawa, Mio; Shen, Chen; Hopkinson, Brian; Matsuda, Yusuke (2014). "Localization of putative carbonic anhydrases in the marine diatom, Thalassiosira pseudonana". Photosynthesis Research. 121 (2–3): 235–249. doi:10.1007/s11120-014-9967-x. PMID 24414291. S2CID 12444516.

Delalat, Bahman; Sheppard, Vonda C.; Ghaemi, Soraya Rasi; Rao, Shasha; Prestidge, Clive A.; McPhee, Gordon; Rogers, Mary-Louise; Donoghue, Jaqueline F.; Pillay, Vinochani; Johns, Terrance G.; Kroeger, Nils; Voelcker, Nicolas H. (2015). "Targeted drug delivery using genetically engineered diatom biosilica". Nature Communications. 6: 8791. Bibcode:2015NatCo...6.8791D. doi:10.1038/ncomms9791. hdl:11343/240712. PMID 26556723.

source: https://en.wikipedia.org/wiki/Thalassiosira_pseudonana

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