Amoebidiidae

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Amoebidiidae
Amoebidium parasiticum.jpg
Amoebidium parasiticum
Scientific classification
Domain:
Eukaryota
(unranked):
Opisthokonta
(unranked):
Holozoa
Class:
Ichthyosporea
Order:
Ichthyophonida
Family:
Amoebidiidae

Lichtenstein 1917 ex Kirk, Canon & David 2001
Genera

Amoebidiidae is a family of single-celled eukaryotes, previously thought to be zygomycete fungi belonging to the class Trichomycetes, but molecular phylogenetic analyses [1] [2] [3] place the family with the opisthokont group Mesomycetozoea [4] (= Ichthyosporea [5] ). The family was originally called Amoebidiaceae, [6] and considered the sole family of the fungal order Amoebidiales that included two genera: Amoebidium and Paramoebidium . However, Amoebidiidae is now monogeneric as it was recently emended to include only Amoebidium (and Paramoebidium is now the sole genus of the family Paramoebidiidae). [7] Species of Amoebidium are considered obligate symbionts of freshwater-dwelling arthropod hosts such as midge larvae and water fleas ( Daphnia ). [8] However, because Amoebidium species attach to the exoskeleton (exterior) of the host and grow in axenic culture, at least some species may be facultative symbionts. [9]

Contents

Etymology

The "amoeb-" prefix refers to the amoeba-like dispersal cells that are produced during the life cycle of Amoebidium. [10]

Description

As the family is monogeneric, the description follows that of the genus, Amoebidium. Amoebidium species are single-celled, cigar-shaped or tubular in vegetative growth form (= thallus), and attach to the exoskeleton of various freshwater arthropod hosts (Crustaecea or Insecta) by means of a secreted, glue-like basal holdfast. [9] The thalli are coenocytic (i.e. lack divisions within the cell) and are unbranched. [9] Sexual reproduction is unknown. Asexual reproduction may proceed along two different routes: 1) the entire content of the cell divides into elongated, uninucleate spores (known as sporangiospores or endospores) with the cell wall breaking apart to release the spores or 2) the entire content of the cell divides to produce teardrop-shaped, motile amoeboid cells that disperse for a short time, then encyst and produce spores from the cyst (called cystospores). [10] [11] Currently there are five described species in the family. [9]

Taxonomic and phylogenetic history

The classification of Amoebidium and Paramoebidium with the fungal trichomycetes was early considered tenuous due to the production of amoeboid dispersal cells, [12] [13] a feature not seen among Fungi. Later studies found no evidence of chitin in the cell wall of these species, further casting doubt on their relatedness to Fungi. [11] [14] However, their overall morphology (i.e. hair-like growth form with a basal holdfast), production of spores, and residence in the digestive tract of arthropods were considered strong enough characters to include them with the fungal trichomycetes until additional evidence could resolve their placement. [15]

In 2000, two independent studies [1] [2] used molecular phylogenetic evidence to show that Amoebidium parasiticum was more closely related to a small clade of animal-associated protist parasites (known as the DRIP clade [16] at the time) than the fungal trichomycetes. In 2005, Cafaro [3] obtained rDNA sequence data from an unidentified Paramoebidium species and it was placed as sister to Amoebidium in the phylogeny. Therefore, Amoebidiaceae was renamed Amoebidiidae [6] to reflect its classification outside of Fungi and with the protist clade that was renamed Mesomycetozoea. [4] The analyses of Cafaro [3] showed a monophyletic relationship between Amoebidium and Paramoebidium, although his dataset had limited taxon sampling with one representative sequence from each genus.

However, a recent molecular phylogenetic analysis of the Ichthyophonida that included broad taxon and gene sampling found evidence of polyphyly between Amoebidium and Paramoebidium. [7] Although topology tests conducted on the dataset (Approximately Unbiased [17] and Shimodaira-Hasegawa [18] tests) did not reject a sister-taxon relationship of the genera, the authors felt there was enough molecular, physiological, and ecological differences to separate the genera into different families. [7] For example, Amoebidium species attach to the exterior of the host whereas Paramoebidium species reside in the digestive tract [8] and ultrastructural analyses found variations in pore arrangement at the spore tips of Amoebidium parasiticum and Paramoebidium curvum. [19]

Related Research Articles

<span class="mw-page-title-main">Opisthokont</span> Group of eukaryotes which includes animals and fungi, among other groups

The opisthokonts are a broad group of eukaryotes, including both the animal and fungus kingdoms. The opisthokonts, previously called the "Fungi/Metazoa group", are generally recognized as a clade. Opisthokonts together with Apusomonadida and Breviata comprise the larger clade Obazoa.

<span class="mw-page-title-main">Ichthyosporea</span> Clade of eukaryote organisms

The Ichthyosporea are a small group of Opisthokonta in Eukaryota, mostly parasites of fish and other animals.

<i>Corallochytrium</i> Genus of unicellular organisms

Corallochytrium belongs to the class of Corallochytrea within Teretosporea and is a sister group to Ichthyosporea. Corallochytrium limacisporum is the only species of Corallochytrium known so far. It was first discovered and named in the Arabian Sea’s coral lagoons by Kaghu-Kumar in 1987. It was first thought to be a member of the fungi-like thraustochytrids, however, this was later disproven due to Corallochytriums lack of cilia and sagenogenetosome. Little research has been done on the life cycle or morphology. Most research concerning this genus has been done to uncover the evolution of animals and fungi, as Corallochytrium possess both animal and fungal enzymatic trademarks.

<span class="mw-page-title-main">Ichthyophonida</span> Order of parasitic animals

Ichthyophonida is an order of parasitic eukaryotes.

Dermocystida is an order of parasitic eukaryotes.

<span class="mw-page-title-main">Filasterea</span> Basal Filozoan clade

Filasterea is a proposed basal Filozoan clade of single-celled ameboid eukaryotes that includes Ministeria and Capsaspora. It is a sister clade to the Choanozoa in which the Choanoflagellatea and Animals appeared, originally proposed by Shalchian-Tabrizi et al. in 2008, based on a phylogenomic analysis with dozens of genes. Filasterea was found to be the sister-group to the clade composed of Metazoa and Choanoflagellata within the Opisthokonta, a finding that has been further corroborated with additional, more taxon-rich, phylogenetic analyses.

<span class="mw-page-title-main">Holozoa</span> Clade containing animals and some protists

Holozoa is a clade of organisms that includes animals and their closest single-celled relatives, but excludes fungi and all other organisms. Together they amount to more than 1.5 million species of purely heterotrophic organisms, including around 300 unicellular species. It consists of various subgroups, namely Metazoa and the protists Choanoflagellata, Filasterea, Pluriformea and Ichthyosporea. Along with fungi and some other groups, Holozoa is part of the Opisthokonta, a supergroup of eukaryotes. Choanofila was previously used as the name for a group similar in composition to Holozoa, but its usage is discouraged now because it excludes animals and is therefore paraphyletic.

Eccrinales are an order of eukaryotes, previously thought to be zygomycete fungi belonging to the class Trichomycetes, but now considered to be members of the opisthokont group Mesomycetozoea.

Smittium is a genus of fungi in the order Harpellales. It is the largest genus in the order. As of 2013, there were 81 described species. Many of these have been formally described only recently; in 1998 there were just 46. Several have been transferred to Smittium from other genera, such as Orphella, Rubetella, Genistella, and Typhella. In general, the genus has a cosmopolitan distribution, but some species are limited to small regions.

<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.

Howard C. Whisler (1931–2007) was an American mycologist. Born in Oakland, California, he attended Berkeley schools and then Palo Alto High School. Howard worked on his undergraduate degree at Oregon State College for two years and then went to the University of California, Berkeley, where he completed a Bachelor of Science degree in plant pathology in 1954. He joined the United States Air Force from 1954 to 1956 stationed in Italy. He returned to University of California, Berkeley after his military life and had finished his doctoral degree with Ralph Emerson in 1960. From 1960 to 1961 he held a post doctoral NATO-NSF Fellowship in France, at the Université de Montpellier. Howard was appointed assistant professor of Botany at McGill University in 1961. He was appointed to the faculty at the University of Washington on March 15, 1963 and worked until he died on September 16, 2007, at the age of 76.

Robert W. Lichtwardt was a Brazilian-born American mycologist specializing in the study of arthropod-associated, gut-dwelling fungi (trichomycetes). He is known for his online monograph and interactive keys to trichomycete taxa.

<i>Creolimax fragrantissima</i> Species of protist

Creolimax fragrantissima is a single-celled protist that occupies a key phylogenetic position to understand the origin of animals. It was isolated from the digestive tract of some marine invertebrates, mainly from the peanut worm, collected from the Northeast Pacific.

<i>Amoebidium</i> Genus of eukaryotes

Amoebidium is a genus of unicellular, symbiotic eukaryotes in the Opisthokont group Mesomycetozoea, family Amoebidiidae. Amoebidium species attach to the exoskeleton of freshwater aquatic arthropods such as midge larvae and water fleas (Daphnia). The type species is Amoebidium parasiticum, which is also one of the only species to be cultured axenically.

<i>Paramoebidium</i> Genus of eukaryotes

Paramoebidium is a genus of unicellular, symbiotic eukaryotes that inhabit the digestive tract of immature freshwater arthropod hosts. Paramoebidium is classified in the opisthokont class Mesomycetozoea, and is the sole genus in the family Paramoebidiidae. Prior to 2005, Paramoebidium species were tentatively placed with the fungal group Trichomycetes due to their habitation of arthropod guts, host overlap between various Paramoebidium and fungal trichomycete taxa, and similar vegetative growth form.

<span class="mw-page-title-main">Paramoebidiidae</span> Family of eukaryotes

Paramoebidiidae is a family of single-celled eukaryotes, previously thought to be zygomycete fungi belonging to the class Trichomycetes, but molecular phylogenetic analyses place the family with the opisthokont group Mesomycetozoea. The family was originally called Amoebidiaceae, and considered the sole family of the fungal order Amoebidiales that included two genera, Amoebidium and Paramoebidium. However, Paramoebidium is now the sole genus of the family Paramoebidiidae and Amoebidiidae is likewise monogeneric as it was recently emended to include only Amoebidium. Species of Paramoebidium are obligate symbionts of immature freshwater-dwelling arthropod hosts such as mayfly and stonefly nymphs and black fly larvae. Paramoebidium species attach to the digestive tract lining of their host via a secreted holdfast.

<i>Abeoforma whisleri</i> Single-celled organism

Abeoforma whisleri is a single-celled eukaryote that belongs to the Ichthyosporea clade, a group of protists closely related to animals.

<i>Pirum gemmata</i>

Pirum gemmata is a unicellular eukaryote that belongs to the Ichthyosporea clade, a group of protists closely related to animals. P. gemmata was isolated from the gut contents of a marine invertebrate, specifically the detritivorous peanut worm Phascolosoma agassizii.

<i>Sphaeroforma arctica</i> Species of protist

Sphaeroforma arctica, is a unicellular eukaryote with a pivotal position in the tree of life. It was first isolated from the arctic marine amphipod Gammarus setosus. Like other Ichthyosporeans such as Creolimax and Abeoforma, Sphaeroforma arctica are spherical cells characterized with their capacity to grow into multi-nucleated coenocytes. However, a unique feature of S. arctica, is that no obvious budding, hyphal, amoeboid, sporal or flagellated growth stages have been observed in laboratory growth conditions.

Hyalochlorella marina, the only species in the genus Hyalochlorella and also known as Dermocystidium sp., is a marine heterotrophic eukaryote with uncertain phylogenic position.

References

  1. 1 2 Benny, G. L., and O'Donnell, K. 2000. Amoebidium parasiticum is a protozoan, not a Trichomycete. Mycologia92: 1133-1137.
  2. 1 2 Ustinova, I, Krienitz, L., and Huss, V. A. R. 2000. Hyaloraphidium curvatum is not a green alga, but a lower fungus; Amoebidium parasiticum is not a fungus, but a member of the DRIPS. Protist151: 253-262.
  3. 1 2 3 Cafaro, M. 2005. Eccrinales (Trichomycetes) are not fungi, but a clade of protists at the early divergence of animals and fungi. Molecular Phylogenetics and Evolution 35: 21-34.
  4. 1 2 Mendoza L, Taylor JW, Ajello L (October 2002). "The class mesomycetozoea: a heterogeneous group of microorganisms at the animal-fungal boundary". Annu. Rev. Microbiol. 56: 315–44. doi:10.1146/annurev.micro.56.012302.160950
  5. ↑ Cavalier-Smith, T. 1998. Neomonada and the origin of animals and fungi. In: Coombs GH, Vickerman K, Sleigh MA, Warren A (ed.) Evolutionary relationships among protozoa. Kluwer, London, pp. 375-407.
  6. 1 2 Will Karlisle Reeves (2003). "Emendation of the family name Amoebidiaceae (Choanozoa, Mesomycetozoa, Ichthyosporea)". Comparative Parasitology . 70 (1): 78–79. doi:10.1654/1525-2647(2003)070[0078:EOTFNA]2.0.CO;2.
  7. 1 2 3 Reynolds, N.K., M.E. Smith, E.D. Tretter, J. Gause, D. Heeney, M.J. Cafaro, J.F. Smith, S.J. Novak, W.A. Bourland, M.M. White. 2017. Resolving relationships at the animal-fungal divergence: A molecular phylogenetic study of the protist trichomycetes (Ichthyosporea, Eccrinida). Molecular Phylogenetics and Evolution in press, available online 20Feb.2017. https://dx.doi.org/10.1016/j.ympev.2017.02.007
  8. 1 2 Lichtwardt, R.W. 2001. Trichomycetes: fungi in relationship with insects and other arthropods. In: Symbiosis. J. Seckbach, ed. Kluwer Academic Publishers, Netherlands, p. 515-588.
  9. 1 2 3 4 Lichtwardt, R.W., M.J. Cafaro, M.M. White. 2001. The Trichomycetes: Fungal Associates of Arthropods Revised Edition. Published online http://www.nhm.ku.edu/%7Efungi/Monograph/Text/Mono.htm Archived 2017-04-26 at the Wayback Machine
  10. 1 2 Lichtenstein, J. L. 1917a. Sur un Amoebidium a commensalisme interne du rectum des larves d'Anaximperator Leach: Amoebidiumfasciculatum n. sp. Archives de Zoologie Expérimentale et Générale56: 49-62.
  11. 1 2 Whisler, H.C., 1963. Observations on some new and unusual enterophilous phycomycetes. Canadian Journal of Botany, 41(6), pp.887–900.
  12. ↑ Léger, L., and Duboscq, O. 1929. L'évolution des Paramoebidium, nouveau genre d'Eccrinides, parasite des larves aquatiques d'Insectes. Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences Paris189: 75-77.
  13. ↑ Cienkowski, L. 1861. Ueber parasitische Schläuche auf Crustaceen und einigen Insektenlarven (Amoebidiumparasiticum m.). Botanische Zeitung19: 169-174.
  14. ↑ Trotter, M.J. & Whisler, H.C., 1965. Chemical composition of the cell wall of Amoebidium parasiticum. Canadian Journal of Botany, (43), pp.869–876.
  15. ↑ Moss, S.T., 1979. Commensalism of Trichomycetes. In L. R. Batra, ed. Insect-Fungus Symbiosis Nutrition, Mutualism, and Commensalism. Montclair: Allanheld, Osmun & Co. Publishers, Inc., pp. 175–227.
  16. ↑ Ragan MA, Goggin CL, Cawthorn RJ, et al. (October 1996). "A novel clade of protistan parasites near the animal-fungal divergence". Proc. Natl. Acad. Sci. U.S.A. 93 (21): 11907–12. doi:10.1073/pnas.93.21.11907
  17. ↑ Shimodaira, H., 2002. An approximately unbiased test of phylogenetic tree selection. Syst. Biol. 51, 492–508.
  18. ↑ Shimodaira, H., Hasegawa, M., 1999. Multiple Comparisons of Log-Likelihoods with Applications to Phylogenetic Inference. Mol. Biol. Evol. 16, 1114–1116.
  19. ↑ Dang, S.-N., Lichtwardt, R.W., 1979. Fine Structure of Paramoebidium (Trichomycetes) and a new species with virus-like particles. Am. J. Bot. 66, 1093-1104.
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