Synura

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Synura
Synura.jpg
A colony of Synura sp.
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Sar
Clade: Stramenopiles
Division: Ochrophyta
Class: Chrysophyceae
Order: Synurales
Family: Synuraceae
Lemmermann, 1899 emend. B.Y. Jo, J.I. Kim, W. Shin, P.Škaloud & P. Siver, 2016 [1]
Genus: Synura
Ehrenberg, 1834
Type species
Synura uvella
Ehrenberg [2]
Species

See text.

Synonyms [3]

Synura is a genus of colonial chrysomonad algae covered with silica scales. [4] Synura is characterized by its heterokont flagella, and is the most conspicuous and diverse genus of the order Synurales. [5]

Contents

Description

Species of Synura form microscopic, spherical colonies, composed of multiple cells attached to each other at the center of the colony. Synura cells are variously shaped, typically spherical to pear-shaped or club-shaped. Each cell contains two plastids aligned with the long axis of the cell; they impart a distinctive golden color to the cells, which comes from chlorophyll c1 and fucoxanthin. Cells are covered with scales made of silica. Two flagella are present. [6]

Identification of species depends on the morphology of the scales. For many species, a positive identification is only possible with an electron microscope, either with scanning electron microscopy (SEM) or transmission electron microscopy (TEM). [6]

Scales

Scales are one of the most distinctive features of Synura cells. They may serve as structural support, protect against grazing and parasitism from other protists and bacteria, and possibly enhance light diffraction into the cell interior, thus improving photosynthetic efficiency. [7] [8]

Silica plays a crucial role in the formation of Synura scales. In media with very low silica concentrations (<0.33 µM Si), scale formation is hindered, and culture growth slows. [9] [10] When silica becomes scarce, Synura cells produce weakly silicified scales and may ultimately fail to produce scales. [10] In contrast to diatoms—whose frustule formation and survival depend on silica—Synura needs silica for building scales but can survive even without it. [9]

Phenotypic plasticity refers to an organism’s ability to alter its traits—such as morphology, physiology, or behavior—in response to environmental changes. [11] In Synura, scale morphology is strongly affected by abiotic factors including temperature, pH, light intensity, and precipitation. [12] [13] As culture temperature rises, the scales of Synura and Mallomonas generally become smaller and more oval or elongated in shape. [14] Interestingly, at higher temperatures (around 25 °C), scale size can increase again, possibly due to temperature-induced irregularities in scale formation. [14] Because of such phenotypic plasticity, it is crucial to account for morphological variation caused by environmental factors, alongside taxonomic differences, when analyzing specimens. [13]

Morphological evolution of silica scales in Synura

Based on multigene phylogenetic analyses and scale morphology, Synura is divided into three major sublineages: Synura, Curtispinae, and Petersenianae. [1] [8] Throughout the evolutionary history of Synura, scale roundness and pore size have been observed to decrease, which may be associated with enhanced protection against viruses and parasites. [8] Another notable trend is the development of a keel, which appears to contribute to increased structural stability of the scales. [8]

Habitat and Ecological significance

Like many other microalgae, Synura serves as a food source for various aquatic organisms. When environmental conditions are optimal for its to growth, certain species can form algal blooms that release ketones, aldehydes, and other organic compounds, leading to strong fishy odors and contamination of water supplies. [15] [16]

Synura is a globally distributed algal genus, and its species can tolerate specific ranges of environmental conditions, allowing them to function as effective bioindicators. Like diatoms, silica scales of Synura resist degradation and persist long after cell death, which can be especially valuable for paleolimnological study.

Classification

Synura is the type and only genus in the family Synuraceae. [1] The present taxonomy recognizes five sections: [4] [5]

References

  1. 1 2 3 Bok Yeon Jo; Jong Im Kim; Pavel Škaloud; Peter A. Siver; Woongghi Shin (1 September 2016). "Multigene phylogeny of Synura (Synurophyceae) and descriptions of four new species based on morphological and DNA evidence". European Journal of Phycology. 51 (4): 413–430. doi:10.1080/09670262.2016.1201700. ISSN   0967-0262. Wikidata   Q99647124.
  2. ↑ Guiry, M.D.; Guiry, G.M. "Synura". AlgaeBase . University of Galway . Retrieved 2024-11-29.
  3. ↑ Pusztai, Martin; Čertnerová, Dora; Škaloudová, Magda; Škaloud, Pavel (2016). "Elucidating the Phylogeny and Taxonomic Position of the genus Chrysodidymus Prowse (Chrysophyceae, Synurales)". Cryptogamie, Algologie. 37 (4): 297–307. Bibcode:2016CrypA..37..297P. doi:10.7872/crya/v37.iss4.2016.297. S2CID   51739744.
  4. 1 2 Škaloud, Pavel; Kristiansen, Jørgen; Škaloudová, Magda (July 2013). "Developments in the taxonomy of silica-scaled chrysophytes – from morphological and ultrastructural to molecular approaches". Nordic Journal of Botany. 31 (4) (published August 2013): 385–402. Bibcode:2013NorJB..31..385S. doi:10.1111/j.1756-1051.2013.00119.x.
  5. 1 2 Škaloud P, Škaloudová M, Procházková A, Němcová Y (2014). "Morphological delineation and distribution patterns of four newly described species within the Synura petersenii species complex (Chrysophyceae, Stramenopiles)". European Journal of Phycology. 49 (2): 213–229. Bibcode:2014EJPhy..49..213S. doi:10.1080/09670262.2014.905710. S2CID   51749551.
  6. 1 2 Siver, Peter A. (2014). "Chapter 14. Synurophyte Algae". In Wehr, John D.; Sheath, Robert G.; Kociolek, J. Patrick (eds.). Freshwater Algae of North America: Ecology and Classification (2 ed.). Elsevier Inc. ISBN   978-0-12-385876-4.
  7. ↑ Knotek, P.; Škaloud, P. (2023). "The effect of patterned structures on the mechanical resistance of microscopic silica scales". Fottea. 23 (2): 190–200. Bibcode:2023Fotte..23..190K. doi:10.5507/fot.2023.007.
  8. 1 2 3 4 Jadrná, I.; Siver, P. A.; Škaloud, P. (2020). "Morphological evolution of silica scales in the freshwater genus Synura (Stramenopiles)". Journal of Phycology. 57 (1): 355–369. doi:10.1111/jpy.13093. PMID   33135154.
  9. 1 2 Leadbeater, B. S. C.; Barker, D. A. N. (1995). "Biomineralization and scale production in the Chrysophyta". Chrysophyte Algae: Ecology, Phylogeny and Development. Cambridge University Press. pp. 141–164. doi:10.1017/cbo9780511752292.008. ISBN   978-0-521-46260-0.
  10. 1 2 Sandgren, C. D.; Barlow, S. B. (1989). "Siliceous scale production in chrysophyte algae. II. SEM observations regarding the effects of metabolic inhibitors on scale regeneration in a laboratory population of scale-free Synura petersenii cells". Nova Hedwigia. 95: 27–44.
  11. ↑ West-Eberhard, M. (2008). "Phenotypic plasticity". Encyclopedia of Ecology. Elsevier. pp. 2701–2707. doi:10.1016/b978-008045405-4.00837-5. ISBN   978-0-08-045405-4.
  12. ↑ Němcová, Y.; Neustupa, J.; Kvíderová, J.; Řezáčová-Škaloudová, M. (2010). "Morphological plasticity of silica scales of Synura echinulata (Synurophyceae) in crossed gradients of light and temperature – a geometric morphometric approach". Nova Hedwigia Beihefte. 136: 21–32. doi:10.1127/1438-9134/2010/0136-0021.
  13. 1 2 Jadrná, I.; Škaloud, P. (2025). "Exploring the factors shaping microscopic morphological traits: insights from the chrysophycean genus Synura (Stramenopiles)". European Journal of Phycology. 60 (1): 67–83. Bibcode:2025EJPhy..60...67J. doi:10.1080/09670262.2024.2442041.
  14. 1 2 Pichrtová, M.; Němcová, Y. (2011). "Effect of temperature on size and shape of silica scales in Synura petersenii and Mallomonas tonsurata (Stramenopiles)". Hydrobiologia. 673 (1): 1–11. Bibcode:2011HyBio.673....1P. doi:10.1007/s10750-011-0743-z.
  15. ↑ Jüttner, F. (1983). "Volatile odorous excretion products of algae and their occurrence in the natural aquatic environment". Water Science & Technology. 15 (6–7): 247–257. Bibcode:1983WSTec..15..247J. doi:10.2166/wst.1983.0149.
  16. ↑ Nicholls, K. H.; Gerrath, J. F. (1985). "The taxonomy of Synura (Chrysophyceae) in Ontario with special reference to taste and odour in water supplies". Canadian Journal of Botany. 63 (8): 1482–1493. Bibcode:1985CaJB...63.1482N. doi:10.1139/b85-205.
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