Vampyrellida | |
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Vampyrella lateritia | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Clade: | Diaphoretickes |
Clade: | SAR |
Phylum: | Endomyxa |
Class: | Vampyrellidea Cavalier-Smith 2018 [1] |
Order: | Vampyrellida West 1901, emend. Hess et al. 2012 [2] |
Clades [3] | |
Diversity [3] | |
48 species | |
Synonyms [4] | |
Aconchulinida De Saedeleer 1934 |
The vampyrellids (order Vampyrellida, class Vampyrellidea), 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. [3] They are also known as aconchulinid amoebae (order Aconchulinida). [4]
Vampyrellids are traditionally considered filose amoebae, i.e. they generate slender pseudopodia (filopodia). They are naked, devoid of external structures such as scales, cell coats or a glycocalyx, although there may be a temporary mucilage coat in the trophozoite stage. The trophozoites vary greatly in shape, size and color between species, but can be grouped into three cell states or 'morphotypes': isodiametric, expanded, and 'filoflabellate'. [2] [3]
All known vampyrellids are heterotrophic amoebae with a free-living (non-parasitic) life cycle that lacks flagellate stages, except for Lateromyxa gallica , and is characterized by an alternation between mobile and immobile cellular stages: [3]
In some species, near the end of the digestive cyst stage, asexual reproduction takes place inside the cyst through a cell division (called 'internal plasmotomy'), resulting in 2–4 daughter cells. These cells are released as young trophozoites through the holes. Other species do not divide inside the closed cyst, and instead divide during or after the hatching process ('external plasmotomy'). Lateromyxa gallica shows an unusual mode of reproduction: while feeding on the inside of algal cells, the plasmodia shed and develop into digestive cysts. [3]
There is a lack of evidence for sexual reproduction in vampyrellids, except for some meiotic stages in resting cysts revealed in Lateromyxa gallica through ultrastructural studies. [5]
Many vampyrellid species have more than one nucleus and behave like plasmodia. They can fuse their cells upon contact, and split apart when moving in opposite directions. Some species readily grow plasmodia as large as a Petri dish under laboratory conditions, while others only fuse when the cell density is high and the food availability is low. It is uncertain to what extend this can happen in the natural environment. In contrast, Placopus species are rarely ever seen with more than two nuclei. [3]
Under adverse environmental conditions, vampyrellids can transform into several types of resting stages: [3]
Vampyrellids have a cosmopolitan distribution: they appear in all continents except Antarctica and all marine ecosystems. They inhabit a wide range of marine, brackish and freshwater habitats, and are frequently isolated from soil samples. [3] Marine ecosystems hold a surprisingly high diversity, [6] and they are found mostly in benthic habitats (e.g. tidal pools, diatom lawns, associated with red algae...). There is a significant positive correlation between the diversity of Vampyrellida and the nutrient availability in the sediment. [7] According to environmental sequencing vampyrellids colonize neotropical soil, [8] glacial cryoconite systems, [9] Brassicaceae leaves, [10] Sphagnum -inhabited peat bogs, [11] hydrothermal sediments [6] and the deep sea. [12]
Vampyrellids display a great trophic diversity. They are predators of a long list of organisms of diverse evolutionary affinities, structures and sizes, including chlorophyte and streptophyte green algae, diatoms, chrysophytes, cryptophytes, euglenids, heterotrophic flagellates, ciliate cysts, fungal hyphae and spores, yeasts, and even micrometazoa such as nematodes and rotifer eggs. Bacterivory is rare and mostly involves filamentous cyanobacteria. Though there are generalist omnivorous predators such as Leptophrys , some vampyrellid species are specialized predators; for example, the algivorous Vampyrella and Placopus are restricted to few species of hard-walled green algae, while Arachnomyxa and Planctomyxa prefer Volvocales and euglenids. [3]
Vampyrellids have evolved strategies to deal with relatively large bulky prey that are difficult to consume. They display at least four different feeding strategies to engulf entire prey or to devour the contents of other eukaryotic cells. These feeding strategies are not mutually exclusive, and the same species can display each with a different type of prey. [3]
Vampyrellids have a long history of research. They are known for the vampire-like feeding habit of several vampyrellid amoebae, which pierce the cell walls of other eukaryotic cells to feed specifically on the cell contents, a feeding mechanism known as protoplast extraction. This similarity lead to the origin of the name for their most popular genus, Vampyrella , and their colloquial name 'vampire amoebae'. [3]
One of the earliest unambiguous reports of a vampyrellid is the mid-19th century description of Amoeba lateritia (now known as Vampyrella lateritia ) by the German botanist Georg Fresenius. [13] The first extensive documentation of their life history and feeding behavior was provided in 1865 by the Polish protozoologist Leon Cienkowski, who created the genus Vampyrella and classified it in a subgroup of the 'monads', [14] a polyphyletic assemblage of parasitoid protists. Posterior works and monographs described numerous aquatic vampyrellid species, with important observations of their behaviour and ecology. In 1885, the German mycologist Wilhelm Zopf demonstrated the presence of nuclei in vampyrellids and erected the first family, Vampyrellidae. [15] [16] [3]
In the mid-20th century the first discoveries of soil-dwelling Vampyrellida were made. The first vampyrellid laboratory culture was established, containing the soil amoeba Theratomyxa weberi that fed on nematodes. Similar soil amoebae were isolated later, and studied as possible pest control against plant-pathogenic nematodes. [17] Other studies identified a giant soil vampyrellid as the organism responsible for perforations found in fungal spores. [18] [3]
In the early 1980s the feeding process and life cycle of the algivorous freshwater Vampyrella lateritia was filmed in unsurpassed detail. [19] [20] At the same time, the genus of large, plasmodial amoebae Thalassomyxa , was discovered in marine waters from remote parts of the world. [21]
Before genetic analyses, the taxonomic placement of vampyrellids was difficult: they were regarded as relatives of myxomycete slime moulds, [16] heliozoa, [22] proteomyxids, [23] filose rhizopods [24] and even monera. [25] In 2009 the mystery was solved through phylogenies of 18S ribosomal RNA genes, which placed vampyrellids as part of Rhizaria. [26] A revised taxonomy in 2012 reconstituted the order Vampyrellida. [2] In 2013, a huge unexpected diversity of marine vampyrellids was detected. [6] [3]
Vampyrellida represents one of the major groups of free-living amoebae, phylogenetically separate from other groups of amoebae such as Amoebozoa, Heterolobosea and Nucleariidae. Instead, Vampyrellida is an isolated clade within the Rhizaria supergroup. [26] They are the closest relatives of the Phytomyxea, parasites of plants and algae that, unlike vampyrellids, disperse through flagellated stages during their life cycle and spend most of their active life within host cells. [3] Current classifications place both Vampyrellida and Phytomyxea, along with other small groups of Rhizaria, within the phylum Endomyxa. [4] Several phylogenetic analyses have recovered a sister group relationship between Vampyrellida and Phytomyxea and have named their clade Proteomyxia [1] or Phytorhiza. [27]
Vampyrellid phylogeny | ||||||||||||||||||||||||||||||||||||
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Phylogeny of Vampyrellida published in 2023, inferred from SSU rRNA gene sequences. [28] The lineages B1, B2 and B4 are clades that contain only environmental DNA sequences, with no described species. [3] |
There are currently 48 credible vampyrellid species distributed in 10 genera, scattered across five well-established clades found through genetic data, four of which are families. Despite the advances, most of the vampyrellid diversity is still unknown or undescribed. [3]
The following taxa have been associated with Vampyrellida, but their placement is uncertain or might not belong to the group. [3]
Nucleariida is a group of amoebae with filose pseudopods, known mostly from soils and freshwater. They are distinguished from the superficially similar vampyrellids mainly by having mitochondria with discoid cristae, in the absence of superficial granules, and in the way they consume food.
The family Vampyrellidae is a subgroup of the order Vampyrellida within the supergroup Rhizaria. Based on molecular sequence data, the family currently comprises the genus Vampyrella, and maybe several other vampyrellid amoebae. The cells are naked and characterised by radiating, filose pseudopodia and an orange colouration of the main cell body.
Cercozoa is a phylum of diverse single-celled eukaryotes. They lack shared morphological characteristics at the microscopic level, and are instead united by molecular phylogenies of rRNA and actin or polyubiquitin. They were the first major eukaryotic group to be recognized mainly through molecular phylogenies. They are the natural predators of many species of bacteria. They are closely related to the phylum Retaria, comprising amoeboids that usually have complex shells, and together form a supergroup called Rhizaria.
Gymnophryidae is a small family of amoeboids that lack shells and produce thin, reticulose pseudopods. These contain microtubules and have a granular appearance, owing to the presence of extrusomes, but are distinct from the pseudopods of Foraminifera. They are included among the Cercozoa, but differ from other cercozoans in having mitochondria with flat cristae, rather than tubular cristae.
Monadofilosa is a grouping of Cercozoa. These organisms are single-celled amoeboid protists.
Protozoan infections are parasitic diseases caused by organisms formerly classified in the kingdom Protozoa. These organisms are now classified in the supergroups Excavata, Amoebozoa, Harosa, and Archaeplastida. They are usually contracted by either an insect vector or by contact with an infected substance or surface.
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.
Protozoa are a polyphyletic group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic debris. Historically, protozoans were regarded as "one-celled animals".
Testate amoebae are a polyphyletic group of unicellular amoeboid protists, which differ from naked amoebae in the presence of a test that partially encloses the cell, with an aperture from which the pseudopodia emerge, that provides the amoeba with shelter from predators and environmental conditions.
Colpodella is a genus of alveolates comprising 5 species, and two further possible species: They share all the synapomorphies of apicomplexans, but are free-living, rather than parasitic. Many members of this genus were previously assigned to a different genus - Spiromonas.
Arachnula is a genus of amoeboid eukaryotes first described by Leon Cienkowski in 1876.
The sarcomonads or class Sarcomonadea are a group of amoeboid biciliate protists in the phylum Cercozoa. They are characterized by a propensity to move through gliding on their posterior cilium or through filopodia, a lack of scales or external theca, a soft cell surface without obvious cortical filamentous or membranous skeleton, two cilia without scales or hairs, tubular mitochondrial cristae, near-spherical extrusomes, and a microbody attached to the nucleus.
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.
Kraken is a genus of amoebae within the Cercozoa, containing the sole species Kraken carinae. These amoebae are characterized by a small round cell body and a network of thin and very long filopodia that can reach up to a mm in diameter. Kraken amoebae feed on bacteria and live in freshwater and soil systems.
Hyalospheniidae is a family of arcellinid testate amoebae and the sole family of the infraorder Hyalospheniformes. Commonly referred to as "hyalospheniids", these lobose amoebae are characterized by their ability to generate a shell composed of either organic matter or siliceous particles that may be recycled from euglyphid amoebae. They inhabit soil or freshwater habitats, and are abundant on Sphagnum mosses.
Vampyrella is a genus of amoebae belonging to the vampyrellid cercozoans usually ranging from 30-60 µm. Members of the genus alternate between two life stages: a free-living trophozoite stage and a cyst stage in which mitosis occurs. This taxon has received a great deal of attention due to their peculiar feeding behaviour of perforating the cell wall of algal cells and drawing out the contents for nourishment.
Vampyrella lateritia is a freshwater species of predatory amoebae that feeds on species of algae and is known for its specialized feeding strategy of removing, digesting, and ingesting the cellular contents of its prey. It is the type species of the genus Vampyrella and has been identified in numerous locations around the world including Brazil, Germany, and the eastern United States. Along with Vampyrella pendula, its genome was sequenced in 2012.
Cryptofilida is an order of small heterotrophic protists in the phylum Cercozoa. They are filose amoebae that lack cilia and gliding, and are instead characterized by movement through branching or unbranched granular filopodia that are appressed to the substrate during their feeding.
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.
Limnofila is a genus of heterotrophic protists that live in freshwater habitats and feed on bacteria. They are also present in the soil ecosystem, where they play an important role as predators of bacteria. They are classified as a single family Limnofilidae and order Limnofilida.