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Amoeba proteus
	Amoeba proteus
Scientific classification
Domain:	Eukaryota
Phylum:	Amoebozoa
Class:	Tubulinea
Order:	Euamoebida
Family:	Amoebidae
Genus:	Amoeba
Species:	A. proteus
Binomial name
	Amoeba proteus; (Pallas, 1766) Leidy, 1878
Synonyms
	Volvox proteus Pallas, 1766 Proteus diffluens O.F. Müller, 1786; Chaos diffluens (O.F. Müller, 1786) Schaeffer, 1926;

Amoeba proteus is a large species of amoeba closely related to another genus of giant amoebae, Chaos. As such, the species is sometimes given the alternative scientific name Chaos diffluens.^[1]^[2]

This protozoan uses extensions called pseudopodia to move and to eat smaller unicellular organisms. Food is enveloped inside the cell's cytoplasm in a food vacuole,^[3] where ingested matter is slowly broken down by enzymes. A. proteus inhabits freshwater environments and feeds on protozoans, algae, rotifers, and even other smaller amoebae. They are colorless, but they may have colored inclusions derived from their food.^[4]

A. proteus possesses a thick-walled nucleus containing granular chromatin, and is therefore a eukaryote. Its membrane consists of a phospholipid bilayer similar to other eukaryotic organisms.^{[citation needed]}

History

The first description of this amoeba is probably that of August Johann Rösel von Rosenhof who, in 1755, published drawings of an amoeboid protozoan he called the "little Proteus".^[5] Subsequently, various authors assigned Rösel's organism and other amoeboid protozoa various names: Carl Linnaeus termed Rösel's organism Chaos protheus in 1758.^[5] Otto Friedrich Müller referred to it as Proteus diffluens in 1786.^[5] In 1878, Joseph Leidy proposed the current name Amoeba proteus to describe Rösel's Proteus, Proteus diffluens, and another described amoeba Amoeba princeps.^[5]^[6]

Molecular mechanisms regulating locomotion in Amoeba proteus

The locomotion of Amoeba proteus exhibits chaotic dynamics described by a low-dimensional chaotic attractor with a correlation dimension around 3-4, indicating that the seemingly random movement arises from deterministic cooperative interactions among a small number of processes like sol-gel transformations, cytoplasmic streaming, and calcium-mediated reactions.^[7] The Arp2/3 complex plays a crucial role in regulating actin polymerization and organization, localizing in the cortical actin network, discrete adhesion foci, and the perinuclear region. However, actin polymerization at the leading edge of migrating pseudopodia occurs independently of the Arp2/3 complex. During migration, changes in the ratio of filamentous actin (F-actin) to total actin correlate with the contractile state of the cell cortex, where an increasing F-actin/total actin ratio corresponds to isometric contraction, while a decreasing ratio indicates isotonic contraction associated with cytoskeleton disintegration.^[8] Furthermore, the Rac/PAK pathway is involved in regulating cell migration, with the PAK kinase MIHCK acting as an effector for the Rac-like protein, and inhibition of MIHCK disrupts normal migration and pseudopod formation, although it does not directly affect actin polymerization.^[9]

Reproduction

Although Amoeba proteus has most of the key proteins associated with sexual processes (as do other amoebae),^[10] no evidence of meiosis or sexual activity has been reported.^{[citation needed]}

Video gallery

Amoeba proteus in motion

Amoeba engulfing a diatom

References

^ Taylor, Monica (August 1927). "The Development of the Nucleus of Amoeba Proteus. Pallas (Leidy) [= Chaos Diffluens (Schaeffer)]". Journal of Cell Science. S2-71 (282): 239–257. doi:10.1242/jcs.s2-71.282.239.
^ "Amoeba proteus (Amoeba) (Chaos diffluens)". Uniprot.org.
^ Nishihara, Eri; Shimmen, Teruo; Sonobe, Seiji (2004). "Functional Characterization of Contractile Vacuole Isolated from Amoeba proteus". Cell Structure and Function. 29 (4): 85–90. doi:10.1247/csf.29.85. PMID 15665503.
^ Rachael (8 February 2023). "Facts about Amoeba". RSScience. Retrieved 2 June 2023.
^ ^a ^b ^c ^d Lorch, I. Joan (1973). "Some Historical Aspects of Amoeba Studies". The Biology of Amoeba. pp. 1–36. doi:10.1016/B978-0-12-384850-5.50007-5. ISBN 978-0-12-384850-5.
^ Leidy, Joseph (April 1878). "Amoeba Proteus". The American Naturalist. 12 (4): 235–238. doi:10.1086/272082. S2CID 222321758.
^ Kłopocka, W.; Moraczewska, J.; Rę;dowicz, M. J. (April 2005). "Characterisation of the Rac/PAK pathway in Amoeba proteus". Protoplasma. 225 (1–2): 77–84. doi:10.1007/s00709-004-0076-0. PMID 15948264.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ Pomorski, P.; Krzemiński, P.; Wasik, A.; Wierzbicka, K.; Barańska, J.; Kłopocka, W. (July 2007). "Actin dynamics in Amoeba proteus motility". Protoplasma. 231 (1–2): 31–41. doi:10.1007/s00709-007-0243-1. PMID 17602277.
^ Miyoshi, Hiromi; Kagawa, Yuki; Tsuchiya, Yoshimi (March 2001). "Chaotic behavior in the locomotion ofamoeba proteus". Protoplasma. 216 (1–2): 66–70. doi:10.1007/BF02680132. PMID 11732198.
^ Hofstatter PG, Brown MW, Lahr DJ (November 2018). "Comparative Genomics Supports Sex and Meiosis in Diverse Amoebozoa". Genome Biol Evol. 10 (11): 3118–3128. doi:10.1093/gbe/evy241. PMC 6263441. PMID 30380054.