Tunicaraptor

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Tunicaraptor
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Amorphea
Clade: Obazoa
(unranked): Opisthokonta
(unranked): Holozoa
Genus: Tunicaraptor
Tikhonenkov et al. 2020
Species:
T. unikontum
Binomial name
Tunicaraptor unikontum
Tikhonenkov et al. 2020 [1]

Tunicaraptor is a genus of marine microbial protists containing the single species Tunicaraptor unikontum, discovered in 2020 from marine waters of Chile. It is a lineage of predatorial flagellates closely related to animals. It has a rare feeding structure not seen in other opisthokonts. [1]

Contents

Morphology

Tunicaraptor unikontum is a small unicellular flagellate composed of oval cells similar to some fungal zoospores, with a length of 3–5 μm. It has one flagellum with a flagellar pocket, and an external envelope or ‘theca’ with long hairs of around 110 nm. Unlike other unicellular opisthokonts, Tunicaraptor cells possess a ‘mouth’, a specialized feeding structure in the anterior part of the cell. There are two centrioles: one develops a flagellum and the other rotates to the kinetosome. The mitochondrial cristae are flat and associated with lipid globules. [1]

Discovery and etymology

Tunicaraptor unikontum was isolated from marine waters of the coast of Chile. Its morphology and phylogenetic relationships were analyzed and published in 2020 in the journal Current Biology . The name Tunicaraptor means ‘predator covered with tunica’, while unikontum (from Latin unus 'one',and Ancient Greek κοντός 'pole') means ‘single flagellum’. [1]

Ecology

Tunicaraptor unikontum is found in marine environments. It is a eukaryovorous predator, meaning it can only feed on other eukaryotes, and it is not capable of consuming bacteria. During feeding, many different cells can aggregate and feed jointly on the same eukaryotic prey. [1]

Evolution

Tunicaraptor is an independent lineage of Holozoan protists, but its placement is not resolved. Three different phylogenetic positions of Tunicaraptor have been obtained from analyses: as sister to Filasterea, as sister to Filozoa or as the sister group to all Holozoa. [1] [2] The characteristics of the Rel homology region of the filasterean Txikispora philomaios was highly similar to Tunicaraptor unikontum, suggesting a phylogenetic relationship between the two species. [3]

Opisthokonta

In search for the genes responsible for animal multicellularity across the eukaryote evolution, a precursor for a neuropeptide gene, nesfatin-1, has also been found in Tunicaraptor unikontum. These discoveries suggest that neuropeptide signaling in animals has a deep evolutionary ancestry in their unicellular relatives. [4]

Related Research Articles

<span class="mw-page-title-main">Stramenopile</span> Clade of eukaryotes

The Stramenopiles, also called Heterokonts, are a clade of organisms distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular surface, and in some they have been secondarily lost. Stramenopiles represent one of the three major clades in the SAR supergroup, along with Alveolata and Rhizaria.

<span class="mw-page-title-main">Excavata</span> Supergroup of unicellular organisms belonging to the domain Eukaryota

Excavata is an extensive and diverse but paraphyletic group of unicellular Eukaryota. The group was first suggested by Simpson and Patterson in 1999 and the name latinized and assigned a rank by Thomas Cavalier-Smith in 2002. It contains a variety of free-living and symbiotic protists, and includes some important parasites of humans such as Giardia and Trichomonas. Excavates were formerly considered to be included in the now obsolete Protista kingdom. They were distinguished from other lineages based on electron-microscopic information about how the cells are arranged. They are considered to be a basal flagellate lineage.

<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">Amorphea</span> Group including fungi, animals and various protozoa

Amorphea is a taxonomic supergroup that includes the basal Amoebozoa and Obazoa. That latter contains the Opisthokonta, which includes the Fungi, Animals and the Choanomonada, or Choanoflagellates. The taxonomic affinities of the members of this clade were originally described and proposed by Thomas Cavalier-Smith in 2002.

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

Telonemia is a phylum of microscopic eukaryotes commonly known as telonemids. They are unicellular free-living flagellates with a unique combination of cell structures, including a highly complex cytoskeleton unseen in other eukaryotes.

<span class="mw-page-title-main">Protist</span> Eukaryotes other than animals, plants or fungi

A protist or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a polyphyletic grouping of several independent clades that evolved from the last eukaryotic common ancestor.

The Urmetazoan is the hypothetical last common ancestor of all animals, or metazoans. It is universally accepted to be a multicellular heterotroph — with the novelties of a germline and oogamy, an extracellular matrix (ECM) and basement membrane, cell-cell and cell-ECM adhesions and signaling pathways, collagen IV and fibrillar collagen, different cell types, spatial regulation and a complex developmental plan, and relegated unicellular stages.

<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.

<span class="mw-page-title-main">Apusomonadidae</span> Group of microorganisms with two flagella

The apusomonads are a group of protozoan zooflagellates that glide on surfaces, and mostly consume prokaryotes. They are of particular evolutionary interest because they appear to be the sister group to the Opisthokonts, the clade that includes both animals and fungi. Together with the Breviatea, these form the Obazoa clade.

<span class="mw-page-title-main">Eukaryote</span> Domain of life whose cells have nuclei

The eukaryotes constitute the domain of Eukarya or Eukaryota, organisms whose cells have a membrane-bound nucleus. All animals, plants, fungi, and many unicellular organisms are eukaryotes. They constitute a major group of life forms alongside the two groups of prokaryotes: the Bacteria and the Archaea. Eukaryotes represent a small minority of the number of organisms, but given their generally much larger size, their collective global biomass is much larger than that of prokaryotes.

<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.

Mantamonads are a group of free-living heterotrophic flagellates that move primarily by gliding on surfaces. They are classified as one genus Mantamonas in the monotypic family Mantamonadidae, order Mantamonadida and class Glissodiscea. Previously, they were classified in Apusozoa as sister of the Apusmonadida on the basis of rRNA analyses. However, mantamonads are currently placed in CRuMs on the basis of phylogenomic analyses that identify their closest relatives as the Diphylleida and Rigifilida.

Colponema is a genus of single-celled flagellates that feed on eukaryotes in aquatic environments and soil. The genus contains 6 known species and has not been thoroughly studied. Colponema has two flagella which originate just below the anterior end of the cell. One extends forwards and the other runs through a deep groove in the surface and extends backwards. Colponema is a predator that feeds on smaller flagellates using its ventral groove. Like many other alveolates, they possess trichocysts, tubular mitochondrial cristae, and alveoli. It has been recently proposed that Colponema may be the sister group to all other alveolates. The genus could help us understand the origin of alveolates and shed light on features that are ancestral to all eukaryotes.

<span class="mw-page-title-main">Marine protists</span> Protists that live in saltwater or brackish water

Marine protists are defined by their habitat as protists that live in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. Life originated as marine single-celled prokaryotes and later evolved into more complex eukaryotes. Eukaryotes are the more developed life forms known as plants, animals, fungi and protists. Protists are the eukaryotes that cannot be classified as plants, fungi or animals. They are mostly single-celled and microscopic. The term protist came into use historically as a term of convenience for eukaryotes that cannot be strictly classified as plants, animals or fungi. They are not a part of modern cladistics because they are paraphyletic.

<i>Syssomonas</i> Genus of protists

Syssomonas is a monotypic genus of unicellular flagellated protists containing the species Syssomonas multiformis. It is a member of Pluriformea inside the lineage of Holozoa, a clade containing animals and their closest protistan relatives. It lives in freshwater habitats. It has a complex life cycle that includes unicellular amoeboid and flagellated phases, as well as multicellular aggregates, depending on the growth medium and nutritional state.

<span class="mw-page-title-main">Colponemid</span> Group of predatorial flagellates

Colponemids are free-living alveolates, unicellular flagellates related to dinoflagellates, apicomplexans and ciliates. They are predators of other small eukaryotes, found in freshwater, marine and soil environments. They do not form a solid clade, but a sparse group of deep-branching alveolate lineages.

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

An amoeboflagellate is any eukaryotic organism capable of behaving as an amoeba and as a flagellate at some point during their life cycle. Amoeboflagellates present both pseudopodia and at least one flagellum, often simultaneously.

Txikispora is a genus of parasitic protists made up solely of the species Txikispora philomaios. It is the only genus in the family Txikisporidae, which is a member of the class Filasterea and is closely related to Ministeriidae. The lineage was first described in 2022 based on specimens identified from the United Kingdom. The species represents a previously undiscovered type of life that diverged extremely early from animals and fungi. It parasitizes amphipods in the genera Echinogammarus and Orchestia and most frequently infects their hemolymph and hemocytes.

References

  1. 1 2 3 4 5 6 Tikhonenkov DV, Mikhailov KV, Hehenberger E, Mylnikov AP, Aleoshin VV, Keeling PJ, et al. (2020). "New Lineage of Microbial Predators Adds Complexity to Reconstructing the Evolutionary Origin of Animals". Current Biology. 30 (22): 4500–4509. Bibcode:2020CBio...30E4500T. doi: 10.1016/j.cub.2020.08.061 . PMID   32976804.
  2. Ros-Rocher N, Pérez-Posada A, Michelle LM, Ruiz-Trillo I (February 2021). "The origin of animals: an ancestral reconstruction of the unicellular-to-multicellular transition". Open Biol. 11 (2): 200359. doi: 10.1098/rsob.200359 . hdl: 10261/251922 . PMC   8061703 . PMID   33622103.
  3. Leger, Michelle; Ros-Rocher, Nuria; Najle, Sebastian (2022). "Rel/NF-kB Transcription Factors Emerged at the Onset of Opisthokonts". Genome Biology and Evolution . 14 (1): 5. doi:10.1093/gbe/evab289. hdl: 10261/272058 .
  4. Yañez-Guerra LA, Thiel D, Jékely G (April 2022). "Premetazoan Origin of Neuropeptide Signaling". Molecular Biology and Evolution. 39 (4): msac051. doi:10.1093/molbev/msac051. PMC   9004410 . PMID   35277960.