Ditylum brightwellii explained

Ditylum brightwellii is a species of cosmopolitan marine centric diatoms. It is a unicellular photosynthetic autotroph that has the ability to divide rapidly and contribute to spring phytoplankton blooms.^[1]

Description

The D. brightwellii cell has a high length to diameter ratio. The cell wall is silicified, as is characteristic of all diatoms. This hard, porous covering is known as the frustule and causes the cell to be more dense than the surrounding water. Oceanic currents and surface winds prevent D. brightwellii cells from sinking beneath the euphotic zone. Cells range in size from 25–100μm in diameter and 80–130μm in length. The valve is most often triangular in shape, but can also be biangular or quadrangular.^[2] A long hollow tube called the rimoportula is located centrally and extends from each valve^[2]

Distribution

Ditylum brightwellii is found in all global oceans except in polar waters.^[3] Genetically distinct populations were observed over the course of a spring bloom in Puget Sound, suggesting that certain genetic lineages are better adapted to certain environmental conditions.

Life cycle

Ditylum brightwellii reproduces primarily asexually, creating clonal lineages. Vegetative cells are capable of enlargement and may also produce resting spores.^[4] However, samples from Puget Sound, WA display high genetic diversity.^[5] This is indicative of sexual reproduction (auxospore formation). Clonal isolates have observed to produce both sperm and eggs.^[6] Two eggs are produced from each oogonium and 64 sperm are produced from each spermatogonangium.^[6] The frequency of sexual reproduction in D. brightwellii is not clear, although conditions including increased nutrients, temperatures ranging from 10 °C-14 °C, and a short photoperiod may be favorable for sexual reproduction.^[6]

Further reading

• Eppley. Richard W.. Holmes. Robert W.. Paasche. Eystein. Periodicity in cell division and physiological behavior of Ditylum brightwellii, a marine planktonic diatom, during growth in light-dark cycles. Archiv für Mikrobiologie. 56. 4. 1967. 305–323. 0302-8933. 10.1007/BF00425206. 22660992 .
• Guo. Ruoyu. Lee. Min-Ah. Ki. Jang-Seu. Normalization genes for mRNA expression in the marine diatom Ditylum brightwellii following exposure to thermal and toxic chemical stresses. Journal of Applied Phycology. 25. 4. 2012. 1101–1109. 0921-8971. 10.1007/s10811-012-9908-z. 254606654 .
• Jung. Seung Won. Youn. Seok Jae. Shin. Hyeon Ho. Yun. Suk Min. Ki. Jang-Seo. Lee. Jin Hwan. Effect of temperature on changes in size and morphology of the marine diatom, Ditylum brightwellii (West) Grunow (Bacillariophyceae). Estuarine, Coastal and Shelf Science. December 2013. 135. 128–136. 10.1016/j.ecss.2013.05.007. 2013ECSS..135..128J.
• Choudhury. Avik Kumar. Pal. Ruma. Phytoplankton and nutrient dynamics of shallow coastal stations at Bay of Bengal, Eastern Indian coast. Aquatic Ecology . 2009 . 44 . 1 . 55–71 . 10.1007/s10452-009-9252-9. 20338877 .

Notes and References

1. Rynearson. Tatiana A.. Tatiana Rynearson. Armbrust. E. Virginia . E. Virginia Armbrust. 2005 . Maintenance of clonal diversity during a spring bloom of the centric diatom Ditylum brightwellii . Molecular Ecology . 14 . 6 . 1631–1640 . 10.1111/j.1365-294X.2005.02526.x . 15836638. 39671471 .
2. Web site: Ditylum J.W.Bailey, 1861: 163 . Algaebase . 4 November 2013.
3. Web site: Ditylum brightwellii . Smithsonian Institution . 25 September 2011 . 4 November 2013.
4. Hargraves PE (1984) Resting spore formation in the marine diatom Ditylum brightwellii (West) Grun. ex V.H. In: Proceedings of the Seventh International Diatom Symposium, Philadelphia, 22–27 August 1982 (ed. Mann DG), pp. 33–46. Otto Koeltz-Science, Koenigstein.
5. Rynearson . T. A. . E. Virginia Armbrust. Newton . J. A. . Armbrust . E. V. . 2006 . Spring bloom development, genetic variation, and population succession in the planktonic diatom Ditylum brightwellii . Limnology and Oceanography . 51 . 3 . 1249–1261 . 10.4319/lo.2006.51.3.1249 . 2006LimOc..51.1249R .
6. Koester. Julie A.. Brawley. Susan H.. Susan Brawley. Karp-Boss. Lee. Mann. David G.. Sexual reproduction in the marine centric diatom Ditylum brightwellii (Bacillariophyta). European Journal of Phycology. 42. 4. 2007. 351–366. 0967-0262. 10.1080/09670260701562100. 80737380 . free.