Willaertia

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Willaertia
Scientific classification
Domain:
Eukaryota
(unranked):
Excavata
Phylum:
Percolozoa
Class:
Heterolobosea
Order:
Schizopyrenida
Family:
Vahlkampfiidae
Genus:
Willaertia

de Jonckheere et al. 1984
Species
  • W. magnade Jonckheere et al. 1984
  • W. minorDobson et al. 1993

Willaertia /ˈwɪləɹʃə/ is a genus of non-pathogenic, free-living, thermophilic amoebae in the family Vahlkampfiidae. [1]

Originally discovered in 1984 by Johan De Jonckheere, their life cycle, like that of other heteroloboseans, has been found to alternate between 3 distinct stages: a cyst, amoeba, and temporary flagellated stage. [2] Willaertia lives in a variety of environments and in recent years has been researched to potentially become a biocide for Legionella pneumophila. [3]

Etymology

The genus name Willaertia was proposed by the original discoverer, De Jonckheere, and was named in memory of Dr. Eddy Willaert. [1]

History

Willaertia was first described in 1984 by Johan F. De Jonckheere, who initially discovered two strains from a sample of bovine faeces and 3 other strains from soil and water samples. [1] Through morphology alone, De Jonckheere determined that W. magna is different from other members of the family Vahlkampfiidae such as Naegleria , to which it is very closely related. [1] These morphological differences included the size of the cyst stage, susceptibility to the drug Berenil, morphological differences in the amoeboid stage, and the apparent lack of a flagellated stage. [1] The distinctiveness of Willaertia was later confirmed through genome analysis. In 1989, De Jonckheere also discovered a temporary flagellated stage of Willaertia. [2] During the 5 year span in which Willaertia had been described, but no flagellated stage was known, R. Michel and W. Raether also performed research on Willaertia without knowing it. [4] They were able to induce a flagellated stage in an amoeba, but they determined it to be a separate genus because one of the key features of the original Willaertia description was its lack of a flagellated stage. Michel and Raether named this genus Protonaegleria and the organism Protonaegleria westphali. [4] When in 1989 De Jonckheere discovered the flagellated stage of Willaertia, [2] he determined that P. westphali and W. magna were in fact the same species. In 1999 genetic analysis confirmed that De Jonckheere was correct. [5] Since then the two names are considered synonyms, Willaertia magna being the correct name for use because of priority reasons.

Habitat and ecology

Willaertia is a thermophilic amoeba and has the capacity to grow in high temperatures, up to 44º Celsius. [3] While it can be found in a variety of locations, typically it lives in thermal swimming pools. [1] The original sample of Willaertia was found in bovine feces, [1] it has been shown that the Vahlkampfiid also lives in freshwater, dog intestines, and soil. [6]

Willaertia has been shown to feed on various microorganisms in its surrounding environment including bacteria and fungi that it is able to phagocytize. It has shown a preference to some particular bacteria such as Legionella pneumophila when it is available. [3] It has been determined that it is not pathogenic towards plants, animals, or humans. [6] [4] [7]

Description of organism

Willaertia has 3 distinct life stages including an amoeboid stage, a temporary flagellated stage, and a cyst stage that it alternates between. [2] Willaertia amoebae are large, often between 50-100 μm. [1] As typical heteroloboseans they have eruptive pseudopods when moving, and as typical vahlkampfiids they form a prominent uroid due to cytoplasmic shifts. [1] Willaertia amoebae have been observed to have spherical and elongated mitochondria that show an unusual crista formation characterized by perforated plates that are either in parallel or alternately packed tubes. [1] They possess Golgi-like saccules but lack the classical Golgi dictyosomes. [1]  Willaertia is often multinucleated, but can also be singularly nucleated, and in the trophozoite stage have very prominent perinuclear granules. [1] They also possess 5 prominent osmiophilic perinuclear globules that lack a bounding membrane. [1] Within the nucleus, the nucleolus is large but loosely organized. [1] A clear distinction from Naegleria is the absence of the interzonal bodies during nuclear division. [1] As of yet, no sexual reproduction has been observed, but asexual reproduction has been described in both the flagellated and the amoeboid stages. [2]

The temporary flagellated stage is often between 16.5 and 25 μm in size with a mean cell volume of 2500 μm3. [2] It usually features 4 flagella and lacks a cytosome, however their size and structure can vary. [2] [8] Primary flagellates form directly from trophozoites and tend to initially present as spheres and slowly assume a more ovoid shape while often slightly flattening posteriorly as they become motile. [2] During the maturation of the flagellated stage, the flagella emerge in 2 pairs. [2] By the time the cell is approximately half of its mature size, the four flagella are equal in length. [2] Like the amoeboid stage, they are capable of asexual division. [2] The nucleus shifts towards the anterior wall and retains its perinuclear granules. [2]

On the surface of the cyst, some surface antigens are shared with those of the genus Naegleria, another member of the family Vahlkampfiidae. [2] Between 18-21 μm in diameter, Willaertia cysts are large for vahlkampfiids, and have numerous pores with a loose ectocyst. [1] The pores are plugged by a pore plug and remain spherical unless in culture, when they have been shown to appear polygonal due to compression. [1]   The aforementioned perinuclear granules disappear as the amoeboid matures into the cyst stage. [1] The cyst has a very thick rough wall that is scattered with lipid globules and rounded mitochondria. [1]

Genetics

The genome of Willaertia magna is the fourth one to be sequenced within the family Vahlkampfiidae. [5] It was found that the genome holds 36.5 megabases with 18,519 predicted bases which is smaller than that of Naegleria gruberi but larger than that of Naegleria fowleri. [9] The Guanine-Cytosine (G-C) content is 25% which is lower than the closely related Naegleria that has a G-C content of 36%. [9] With a phylogenetic analysis based on the partial 18S rRNA gene, it was determined that W. magna was most closely related to Naegleria species. [9]

Of the 13,571 sequenced proteins W. magna has been found to have, 67.7% of these are shared with eukaryotes and 5.1% are shared with bacteria. [9] Currently, the number of chromosomes is unknown, though it has been estimated to be between 15-23. [10] It has been suggested that the chromosomal shape is circular though this has not been confirmed. Recent research has shown that the highest numbers of genes within the W. magna genome are involved with post-translational modifications (1,060 genes). [9]

Practical importance

Recently, research has been done into the applications of certain strains of W. magna being used as biocontrol agents or biocides. The W. magna C2c Maky strain has demonstrated a unique ability to be able to eliminate Legionella pneumophila strains. [3] As the causative agent of Legionnaire’s disease, L. pneumophila can be quite an issue for humans as it is often found in cooling tower water. Due to the high temperatures experienced within the cooling towers, W. magna, as it is thermophilic, does quite well and has the capacity to grow, a trait that the majority of organisms do not possess. [3] L. pneumophila often uses other amoebae as vectors to spread, but W. magna can fully digest the pathogen inside food vacuoles. [3] W. magna has been considered a safe candidate for this type of application as it is a non-pathogenic amoeba for both humans and animal species. This has been further confirmed with genetic analysis and would decrease the use of chemical biocides if implemented. [3]

Currently, more research is underway to explore if W. magna can also be used as a biocontrol agent against pathogens in crops that are resistant to fungicides, for example rust fungi that affect both soybeans and wheat.

List of Species

Related Research Articles

<span class="mw-page-title-main">Percolozoa</span> Phylum of Excavata

The Percolozoa are a group of colourless, non-photosynthetic Excavata, including many that can transform between amoeboid, flagellate, and cyst stages.

<i>Legionella</i> Pathogenic genus of gram-negative bacteria and the related disease

Legionella is a genus of pathogenic gram-negative bacteria that includes the species L. pneumophila, causing legionellosis including a pneumonia-type illness called Legionnaires' disease and a mild flu-like illness called Pontiac fever.

<span class="mw-page-title-main">Dictyostelid</span> Group of slime moulds

The dictyostelids or cellular slime molds are a group of slime molds or social amoebae.

<i>Acanthamoeba</i> Genus of protozoans

Acanthamoeba is a genus of amoebae that are commonly recovered from soil, fresh water, and other habitats. The genus Acanthamoeba has two stages in its life cycle, the metabolically active trophozoite stage and a dormant, stress-resistant cyst stage. In nature, Acanthamoeba species are generally free-living bacterivores. However, they are also opportunistic pathogens able to cause serious and sometimes fatal infections in humans and other animals.

Free-living amoebae are a group of protozoa that are important causes of infectious disease in humans and animals.

<span class="mw-page-title-main">Naegleriasis</span> Rare and usually fatal brain infection by a protist

Naegleriasis, also known as primary amoebic meningoencephalitis (PAM), is an almost invariably fatal infection of the brain by the free-living unicellular eukaryote Naegleria fowleri. Symptoms are meningitis-like and include headache, fever, nausea, vomiting, a stiff neck, confusion, hallucinations and seizures. Symptoms progress rapidly over around five days, and death usually results within one to two weeks of symptoms.

<i>Naegleria</i> Genus of protists

Naegleria is a free living amoebae protist genus consisting of 47 described species often found in warm aquatic environments as well as soil habitats worldwide. It has three life cycle forms: the amoeboid stage, the cyst stage, and the flagellated stage, and has been routinely studied for its ease in change from amoeboid to flagellated stages. The Naegleria genera became famous when Naegleria fowleri, a human pathogenic strain and the causative agent of primary amoebic meningoencephalitis (PAM), was discovered in 1965. Most species in the genus, however, are nonpathogenic, meaning they do not cause disease.

<i>Legionella pneumophila</i> Species of bacterium

Legionella pneumophila is an aerobic, pleomorphic, flagellated, non-spore-forming, Gram-negative bacterium of the genus Legionella. L. pneumophila is the primary human pathogen in the genus Legionella. In nature, L. pneumophila infects soil amoebae of the genus Acanthamoeba and freshwater amoeboflagellates of the genus Naegleria. This pathogen is thus found commonly near freshwater environments and invades the unicellular life found in these environments, using them to carry out metabolic functions.

<i>Amoeba proteus</i> Species of amoeba

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.

<i>Amoeba</i> (genus) Genus of Protozoa

Amoeba is a genus of single-celled amoeboids in the family Amoebidae. The type species of the genus is Amoeba proteus, a common freshwater organism, widely studied in classrooms and laboratories.

<i>Naegleria gruberi</i> Species of protist

Naegleria gruberi is a species of Naegleria. It is famous for its ability to change from an amoeba, which lacks a cytoplasmic microtubule cytoskeleton, to a flagellate, which has an elaborate microtubule cytoskeleton, including flagella. This "transformation" includes de novo synthesis of basal bodies.

<i>Mastigamoeba</i> Genus of flagellar amoeboids

Mastigamoeba is a genus of pelobionts, and treated by some as members of the Archamoebae group of protists. Mastigamoeba are characterized as anaerobic, amitochondriate organisms that are polymorphic. Their dominant life cycle stage is as an amoeboid flagellate. Species are typically free living, though endobiotic species have been described.

Psalteriomonas is a genus of excavates in the group of Heterolobosea. The genus was first discovered and named in 1990. It contains amoeboflagellate cells that live in freshwater anaerobic sediments all over the world. The microtubule-organizing ribbon and the associated microfibrillar bundles of the mastigote system is the predominant feature in Psalteriomonas. This harp-shaped complex gives rise to the name of this genus. Psalteriomonasforms an endosymbiotic relationship with methanogenic bacteria, especially with Methanobacterium formicicum There are currently three species in this genus: P. lanterna, P. vulgaris, and P. magna.

<span class="mw-page-title-main">Vampyrellida</span> Order of single-celled organisms

The vampyrellids, colloquially known as vampire amoebae, are a group of free-living predatory amoebae classified as part of the lineage Endomyxa. They are distinguished from other groups of amoebae by their irregular cell shape with propensity to fuse and split like plasmodial organisms, and their life cycle with a digestive cyst stage that digests the gathered food. They appear worldwide in marine, brackish, freshwater and soil habitats. They are important predators of an enormous variety of microscopic organisms, from algae to fungi and animals. They are also known as aconchulinid amoebae.

Legionella anisa is a Gram-negative bacterium, one of more than 40 species in the family Legionellaceae. After Legionella pneumophila, this species has been isolated most frequently from water samples. This species is also one of the several pathogenic forms of Legionella having been associated with rare clinical cases of illness including Pontiac fever and Legionnaires' disease.

Legionella cherrii is an aerobic, flagellated, Gram-negative bacterium from the genus Legionella. It was isolated from a heated water sample in Minnesota. L. cherrii is similar to another Legionella species, L. pneumophila, and is believed to cause major respiratory problems.

<span class="mw-page-title-main">Amoeba</span> Cellular body type

An amoeba, often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudopods. Amoebae do not form a single taxonomic group; instead, they are found in every major lineage of eukaryotic organisms. Amoeboid cells occur not only among the protozoa, but also in fungi, algae, and animals.

<i>Naegleria fowleri</i> Species of free-living excavate form of protist

Naegleria fowleri, also known as the brain-eating amoeba, is a species of the genus Naegleria. It belongs to the phylum Percolozoa and is technically classified as an amoeboflagellate excavate, rather than a true amoeba. This free-living microorganism primarily feeds on bacteria but can become pathogenic in humans, causing an extremely rare, sudden, severe, and usually fatal brain infection known as naegleriasis or primary amoebic meningoencephalitis (PAM).

Legionella clemsonensis was isolated in 2006, but was described in 2016 by Clemson University researchers. It is a Gram-negative bacterium.

<span class="mw-page-title-main">Symbiosis in Amoebozoa</span>

Amoebozoa of the free living genus Acanthamoeba and the social amoeba genus Dictyostelium are single celled eukaryotic organisms that feed on bacteria, fungi, and algae through phagocytosis, with digestion occurring in phagolysosomes. Amoebozoa are present in most terrestrial ecosystems including soil and freshwater. Amoebozoa contain a vast array of symbionts that range from transient to permanent infections, confer a range of effects from mutualistic to pathogenic, and can act as environmental reservoirs for animal pathogenic bacteria. As single celled phagocytic organisms, amoebas simulate the function and environment of immune cells like macrophages, and as such their interactions with bacteria and other microbes are of great importance in understanding functions of the human immune system, as well as understanding how microbiomes can originate in eukaryotic organisms.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 De Jonckheere JF, Dive DG, Pussard M, Vickerman K (1984). "Willaertia magna gen. nov., sp. Nov. (Vahlkampfiidae). A thermophilic amoeba found in different habitats". Protistologica. 20 (1): 5–13.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 Robinson BS, Christy PE, De Jonckheere JF (January 1989). "A temporary flagellate (mastigote) stage in the vahlkampfiid amoeba Willaertia magna and its possible evolutionary significance". Bio Systems. 23 (1): 75–86. doi:10.1016/0303-2647(89)90010-5. PMID   2624890.
  3. 1 2 3 4 5 6 7 Hasni I, Jarry A, Quelard B, Carlino A, Eberst JB, Abbe O, Demanèche S (February 2020). "Willaertia magna C2c Maky". Pathogens. 9 (2): 105. doi: 10.3390/pathogens9020105 . PMC   7168187 . PMID   32041369.
  4. 1 2 3 Michel R, Raether W (November 1985). "Protonaegleria westphali gen. nov., sp. nov.(Vahlkampfiidae) a thermophilic amoebo-flagellate isolated from freshwater habitat in India". Zeitschrift für Parasitenkunde. 71 (6): 705–13. doi:10.1007/BF00926796. S2CID   44723205.
  5. 1 2 Brown S, De Jonckheere JF (February 1999). "A reevaluation of the amoeba genus Vahlkampfia based on SSUrDNA sequences". European Journal of Protistology. 35 (1): 49–54. doi:10.1016/S0932-4739(99)80021-2.
  6. 1 2 Niyyati M, Lorenzo-Morales J, Haghi AM, Valladares B (2009). "Isolation of Vahlkampfiids (Willaertia magna) and Thecamoeba from soil samples in Iran". Iranian Journal of Parasitology. 4 (1): 48–52.
  7. ↑ Hasni, Issam; Chelkha, Nisrine; Baptiste, Emeline; Mameri, Mouh Rayane; Lachuer, Joel; Plasson, Fabrice; Colson, Philippe; La Scola, Bernard (2019-12-04). "Investigation of potential pathogenicity of Willaertia magna by investigating the transfer of bacteria pathogenicity genes into its genome". Scientific Reports. 9 (1): 18318. doi: 10.1038/s41598-019-54580-6 . ISSN   2045-2322. PMC   6892926 . PMID   31797948.
  8. ↑ De Jonckheere JF, Brown S (March 1995). "Willaertia minor is a species of Naegleria". European Journal of Protistology. 31 (1): 58–62. doi:10.1016/S0932-4739(11)80357-3.
  9. 1 2 3 4 5 Hasni I, Chelkha N, Baptiste E, Mameri MR, Lachuer J, Plasson F, et al. (December 2019). "Investigation of potential pathogenicity of Willaertia magna by investigating the transfer of bacteria pathogenicity genes into its genome". Scientific Reports. 9 (1): 18318. Bibcode:2019NatSR...918318H. doi:10.1038/s41598-019-54580-6. PMC   6892926 . PMID   31797948.
  10. ↑ De Jonckheere JF (January 1989). "Variation of electrophoretic karyotypes among Naegleria spp". Parasitology Research. 76 (1): 55–62. doi:10.1007/BF00931073. PMID   2622896. S2CID   22632942.
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