''Ancoracysta twista'' is a

eukaryotic Eukaryotes () are organisms whose Cell (biology), cells have a cell nucleus, nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the ...

microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

. It is a predatory protist that appears to be sister to

Haptista Haptista is a proposed group of protists made up of centrohelids and haptophytes. Phylogenomic studies indicate that Haptista, together with ''Ancoracysta twista'', forms a sister clade to the SAR+Telonemia supergroup, but it may also be siste ...

.Janouškovec J, Tikhonenkov DV, Burki F, Howe AT, Rohwer FL, Mylnikov AP, Keeling PJ. "A New Lineage of Eukaryotes Illuminates Early Mitochondrial Genome Reduction", ''Current Biology'' 2017,

Description

''Ancoracysta twista'' was first described in November 2017 in ''

Current Biology ''Current Biology'' is a biweekly peer-reviewed scientific journal that covers all areas of biology, especially molecular biology, cell biology, genetics, neurobiology, ecology, and evolutionary biology. The journal includes research articles, ...

''. It was found in a sample collected from the surface of a tropical aquarium

brain coral Brain coral is a common name given to various corals in the families Mussidae and Merulinidae, so called due to their generally spheroid shape and grooved surface which resembles a brain. Each head of coral is formed by a colony of genetically ...

. It actively feeds on '' Procryptobia sorokini'', probably immobilising its prey through discharging a previously unknown type of

extrusome Extrusomes are membrane-bound structures in some eukaryotes which, under certain conditions, discharge their contents outside the cell. There are a variety of different types, probably not homologous, and serving various functions. Notable extru ...

named an ancoracyst. Genetic analysis shows that it is not closely related to any known lineage, but it may be most closely related to a grouping of

haptophyte The haptophytes, classified either as the Haptophyta, Haptophytina or Prymnesiophyta (named for '' Prymnesium''), are a clade of algae. The names Haptophyceae or Prymnesiophyceae are sometimes used instead. This ending implies classification at ...

s and

centrohelid The centrohelids or centroheliozoa are a large group of heliozoan protists. They include both mobile and sessile forms, found in freshwater and marine environments, especially at some depth. Characteristics Individuals are unicellular and spher ...

s (

). It is notable for having a gene-rich

mitochondrial genome Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial ...

, the largest known outside the

jakobid Jakobids are an order of free-living, heterotrophic, flagellar eukaryotes in the supergroup Excavata. They are small (less than 15 μm), and can be found in aerobic and anaerobic environments. The order Jakobida, believed to be monophyletic, cons ...

s or ''

Diphylleia rotans ''Diphylleia rotans'' is a eukaryotic microorganism. It is notable for having a gene-rich mitochondrial genome, the largest known outside the jakobid Jakobids are an order of free-living, heterotrophic, flagellar eukaryotes in the supergroup Ex ...

''. Uniquely, it appears to contain both the nucleus-encoded holocytochrome ''c'' synthase system III ''and'' the mitochondrion-encoded bacterial cytochrome ''c'' maturation system I.

Taxonomy

A 2018 study from Cavalier-Smith, Chao & Lewis created a new subphylum and subsequent lower taxonomic ranks for ''Ancoracysta twista''. They also created a new combination for ''

Colponema marisrubri ''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 ...

'' (Mylnikov & Tikhonenkov, 2009), which was shown to be ultrastructurally similar and phylogenetically close to ''A. twista'', thus renaming it ''A. marisrubri''. A 2022 study placed ''A. twista'' in a new supergroup

Provora Provora is a proposed supergroup of eukaryotes made up of predatory microbes, "devouring voracious protists". It was reported that ten strains were isolated and cultured in 2022. They are predators of other microorganisms. Their discovery was ve ...

References

External links

* * Katarina Zimmer; Denis Tikhonenkov (image)
A Newly Identified Species Represents Its Own Eukaryotic Lineage — The 10-micrometer-long flagellate cell might have a big story to tell about the evolution of eukaryotes
On: The Scientist. Nov 20, 2017 {{Taxonbar, from=Q47487266 Protists described in 2017 Diaphoretickes