Syssomonas: Difference between revisions
←Created page with '{{Short description|Genus of protists}} {{Speciesbox|taxon=Syssomonas multiformis|authority=Tikhonenkov, Hehenberger, Mylnikov & Keeling 2017<ref name="Hehenberger-2017"/>|display_parents=7|image=Syssomonas_2X_2020.webp|image_caption=SEM image of ''Syssomonas''.<br>ac = acroneme, fl = flagellum}} '''''Syssomonas''''' is a monotypic genus of unicellular flagellated protists containi...' |
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{{Short description|Genus of protists}} |
{{Short description|Genus of protists}} |
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{{Speciesbox|taxon=Syssomonas multiformis|authority=Tikhonenkov, Hehenberger, Mylnikov & Keeling 2017<ref name="Hehenberger-2017"/>|display_parents= |
{{Speciesbox|taxon=Syssomonas multiformis|authority=Tikhonenkov, Hehenberger, Mylnikov & Keeling 2017<ref name="Hehenberger-2017"/>|display_parents=4|image=Syssomonas_2X_2020.webp|image_caption=[[Scanning electron microscope|SEM]] image of ''Syssomonas''.<br>ac = [[acroneme]], fl = [[flagellum]]|type_strain=Colp-12<br>MI-PR205{{efn|Deposited in the Marine Invertebrate |
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Collection, [[Beaty Biodiversity Museum]], [[University of British Columbia]]<ref name="Hehenberger-2017"/>}}}} |
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'''''Syssomonas''''' is a [[monotypic]] [[genus (biology)|genus]] of [[unicellular]] [[flagellate]]d [[protist]]s containing the [[species (biology)|species]] '''''Syssomonas multiformis'''''. It is a lineage of [[Holozoa]], a [[clade]] containing [[animal]]s and their closest unicellular relatives.<ref name="Hehenberger-2017"/><ref name="Tikhonenkov-2020"/> |
'''''Syssomonas''''' is a [[monotypic]] [[genus (biology)|genus]] of [[unicellular]] [[flagellate]]d [[protist]]s containing the [[species (biology)|species]] '''''Syssomonas multiformis'''''. It is a lineage of [[Holozoa]], a [[clade]] containing [[animal]]s and their closest unicellular relatives. It lives in [[freshwater]] habitats and has a complex [[biological life cycle|life cycle]] with [[amoeboid]] and [[flagellate]]d phases.<ref name="Hehenberger-2017"/><ref name="Tikhonenkov-2020"/> |
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== Life cycle == |
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''Syssomonas multiformis'' is a [[species (biology)|species]] of [[unicellular]] protists with naked cells (lacking any [[Test (biology)|shell]] or scales) and a large variety of life forms during their highly complex [[biological life cycle|life cycle]]. These forms include: round flagellate cells (7–14 μm in diameter) with one [[posterior (anatomy)|posterior]] [[flagellum]], amoeboflagellate cells, [[amoeboid]] non-flagellar cells, and spherical [[microbial cyst|cysts]]. They can also form clusters of multiple cells.<ref name="Hehenberger-2017"/><ref name="Tikhonenkov-2020"/> |
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=== Unicellular stages: flagellar, amoeboid and cyst === |
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[[File:Syssomonas life forms.png|thumb|upright=2.0|External morphology and life forms of ''Syssomonas multiformis''. A-B-C: swimming flagellated cells. D: amoeboflagellate (lb = [[lobopodia]]). E-F: amoeboid cells (fp = [[filopodia]]). G: [[microbial cyst|cyst]]. H: palintomic [[cell division]] inside a cyst. I: cyst with vesicles. J: attached flagellated cell.]] |
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In the uniflagellar swimming stage, the most common stage of the cycle, the cells of ''Syssomonas'' resemble a typical opisthokont cell, reminiscent of [[animal]] [[sperm cell]]s or [[chytrid]] [[zoospore]]s. The [[flagellum]] is smooth and emerges from the middle-lateral point of the [[cell (biology)|cell]], turns back, and directs backwards during swimming. While swimming, the fast beating of the flagellum can create the appearance of two flagella. The swimming cells rotate, and can suddenly stop and change direction of the movement. Solitary cells can attach temporarily to a substrate through the [[anterior (anatomy)|anterior]] part of the cell body, and produce water flow by rapid flagellar beating, resembling [[choanoflagellates]] or [[choanocyte]]s from [[sponge]]s. Floating cells move downwards to transform into amoeboflagellates by generating wide [[lobopodia]] and thin short [[filopodia]], and slowing the flagellar beating. The amoeboflagellates can crawl along the substrate through their anterior lobopodia.<ref name="Tikhonenkov-2020"/> |
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The amoeboflagellate stages of ''Syssomonas'' can lose the flagellum by three different ways: discarding it abruptly, retracting it into the cell when stretched out, or convolve under the cell and then retract into the cell as a spiral. As a result they become the [[amoeboid]] stage, which produces thin short filopodia and sometimes have two [[contractile vacuole]]s. Both amoebae and amoeboflagellates can turn back into flagellates.<ref name="Tikhonenkov-2020"/> |
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The amoeboid stage can retract its filopodia and become a round [[microbial cyst|cyst]], in which palintomic cell division (i.e. rapid [[cell division]]s without [[cytoplasm]]ic growth in between, a characteristic of animal [[cleavage (embryo)|embryonic cleavage]])<ref>{{cite journal|title=Cell differentiation and germ–soma separation in Ediacaran animal embryo-like fossils|vauthors=Chen L, Xiao S, Pang K, Zhou C, Yuan X|pages=238–241|date=September 2014|journal=Nature|volume=516|doi=10.1038/nature13766}}</ref> can occur, generating 2, 4, 8 or 16 flagellated cells that are released from inside the cyst.<ref name="Tikhonenkov-2020"/> |
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=== Aggregative multicellular stages === |
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[[File:Syssomonas aggregates.webp|thumb|upright=2.0|K-M, O: cellular aggregations of ''Syssomonas'' near the bottom of the [[Petri dish]]. N: floating aggregate of flagellated cells.]] |
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Cells of ''Syssomonas'' can merge partially and form temporary aggregations of about 3–10 cells, usually shapeless and observed near the bottom of the water column. They can also aggregate by joining only flagellated cells together, with their flagella directed outwards, resembling the rosette-like colonies of [[choanoflagellates]]. Both aggregations break up easily, and their [[cell membrane]]s are not fused.<ref name="Tikhonenkov-2020"/> |
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In solid cultures, solitary cells can sometimes merge completely at the bottom of the [[Petri dish]] into a [[syncytium]]-like or [[pseudoplasmodium]] structure, in which the [[nucleus (cell)|nuclei]] do not merge. From these syncytia, [[budding]] of daughter cells occurs. This phenomenon of budding from syncytia has not been observed in any other eukaryotes, although the formation of multinucleated cells as a result of aggregation of multiple cells is known in other protist lineages ([[dictyostelid]]s in [[Eumycetozoa]], ''[[Copromyxa]]'' in [[Tubulinea]],<ref name="Brown-2011"/> [[acrasid]]s in [[Excavata]],<ref name="Brown-2012-Acrasidae"/> ''[[Sorogena]]'' in [[Alveolata]],<ref name="Lasek-Nesselquist-2001"/> ''[[Sorodiplophrys]]'' in [[Stramenopiles]], ''[[Guttulinopsis]]'' in [[Rhizaria]],<ref name="Brown-2012-Rhizaria"/> and ''[[Fonticula alba]]'' within the opisthokonts).<ref name="Schaap-2006"/> The transition from an amoeboid [[filopodia]]l stage to an aggregative stage is also observed in another holozoan, ''[[Capsaspora owczarzaki]]''. Syncytia are not unusual in animals either; the cytoplasm of [[glass sponge]]s, [[Tegument (helminth)|teguments]] of [[flatworm]]s, and the [[skeletal muscle]]s and [[placenta]] of [[mammals]] are syncytial structures.<ref name="Tikhonenkov-2020"/> |
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The merging of cells in ''Syssomonas'' attracts, again, likely by [[chemotaxis|chemical signaling]], other nearby cells that actively swim and try to attach to the aggregates. This appears to be the only method by which aggregates grow, as opposed to [[cell division]].<ref name="Tikhonenkov-2020"/> |
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== Ecology == |
== Ecology == |
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''Syssomonas multiformis'' was isolated from a [[freshwater]] pool in [[Vietnam]]. The organism feeds on the cytoplasmic content of other [[eukaryote]]s of similar size, which is an unusual trait among unicellular [[holozoa]]ns. They can also engulf [[bacteria]] and small detritus, in a similar manner to [[choanoflagellate]]s.<ref name="Hehenberger-2017"/> |
''Syssomonas multiformis'' was isolated from a [[freshwater]] pool in [[Vietnam]]. The organism can survive temperatures ranging from 5 to 36 °C. It feeds on the cytoplasmic content of other [[eukaryote]]s of similar size, which is an unusual trait among unicellular [[holozoa]]ns. In particular, it is a predator of [[heterotrophic]] [[chrysomonad]]s and [[bodonid]]s (e.g. ''[[Parabodo caudatus]]'' and ''[[Spumella]]'' species).<ref name="Tikhonenkov-2020"/> They can also engulf [[bacteria]] and small detritus, in a similar manner to [[choanoflagellate]]s.<ref name="Hehenberger-2017"/> |
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In contrast to many other eukaryotic protists, ''Syssomonas'' cells do not possess any extrusive [[organelle]]s for hunting. Instead, they attach to the prey cell and sucks out their cytoplasm without ingesting the [[cell membrane]]. They feed better on inactive, slow or dead cells or cysts. Likely by [[chemotaxis|chemical signaling]], after one cell attaches to the prey, many other ''Syssomonas'' cells become attracted to the same prey cell and try to attach to it. Several cells can suck out the cytoplasm of the same prey cell jointly.<ref name="Tikhonenkov-2020"/> |
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They use short [[pseudopodia]] to feed on clusters of [[bacteria]]. Afterwards, they form a large [[food vacuole]] at the [[posterior (anatomy)|posterior]] cell end. However, bacteria alone are not sufficient nutrition for ''Syssomonas'': without any eukaryotic prey, their cells die or form [[resting cyst]]s.<ref name="Tikhonenkov-2020"/> |
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== Evolution == |
== Evolution == |
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As a lineage of Holozoa, ''Syssomonas'' is one of many protist groups closely related to [[animal]]s and is therefore a subject of research in the search for the origin of animal [[multicellularity]].<ref name="Hehenberger-2017"/> |
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The first [[phylogenomic]] analyses including ''Syssomonas'' recovered the genus as the [[sister taxon]] of ''[[Corallochytrium]]''. Together, they compose the clade [[Pluriformea]], which was recovered as the sister taxon of [[Filozoa]].<ref name="Hehenberger-2017"/> An alternative hypothesis places Pluriformea as the sister group of [[Ichthyosporea]] in a clade known as [[Teretosporea]].<ref name="Tikhonenkov-2020"/> |
The first [[phylogenomic]] analyses including ''Syssomonas'' recovered the genus as the [[sister taxon]] of ''[[Corallochytrium]]''. Together, they compose the clade [[Pluriformea]], which was recovered as the sister taxon of [[Filozoa]].<ref name="Hehenberger-2017"/> An alternative hypothesis places Pluriformea as the sister group of [[Ichthyosporea]] in a clade known as [[Teretosporea]].<ref name="Tikhonenkov-2020"/> |
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{{clade|style=font-size:90%;|label1=[[Opisthokonta]]|1={{clade |
{{clade|style=font-size:90%;|label1=[[Opisthokonta]]|1={{clade |
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== Notes == |
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{{notelist}} |
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== References == |
== References == |
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{{reflist|refs= |
{{reflist|refs= |
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<ref name="Tikhonenkov-2020">{{cite journal|vauthors=Tikhonenkov DV, Hehenberger E, Esaulov AS, Belyakova OI, Mazei YA, Mylnikov AP, Keeling PJ|title=Insights into the origin of metazoan multicellularity from predatory unicellular relatives of animals|journal=BMC Biology|volume=18|pages=39|date=2020|doi=10.1186/s12915-020-0762-1}}</ref> |
<ref name="Tikhonenkov-2020">{{cite journal|vauthors=Tikhonenkov DV, Hehenberger E, Esaulov AS, Belyakova OI, Mazei YA, Mylnikov AP, Keeling PJ|title=Insights into the origin of metazoan multicellularity from predatory unicellular relatives of animals|journal=BMC Biology|volume=18|pages=39|date=2020|doi=10.1186/s12915-020-0762-1}}</ref> |
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<ref name="Brown-2011">{{cite journal|vauthors=Brown MW, Silberman JD, Spiegel FW|title=“Slime molds” among the Tubulinea (Amoebozoa): molecular systematics and taxonomy of Copromyxa|journal=Protist|date=April 2011|volume=162|pages=277–287|doi=10.1016/j.protis.2010.09.003|issue=2}}</ref> |
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<ref name="Brown-2012-Rhizaria">{{cite journal|vauthors=Brown MW, Kolisko M, Silberman JD, Roger AJ|title=Aggregative Multicellularity Evolved Independently in the Eukaryotic Supergroup Rhizaria|journal=Current Biology|volume=22|issue=12|date=2012|pages=1123–1127|doi=10.1016/j.cub.2012.04.021|pmid=22608512 |s2cid=17510471 }}</ref> |
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<ref name="Brown-2012-Acrasidae">{{cite journal|vauthors=Brown MW, Silberman JD, Spiegel FW|title=A contemporary evaluation of the acrasids (Acrasidae, Heterolobosea, Excavata)|journal=European Journal of Protistology|date=May 2012|volume=48|issue=2|pages=103–123|pmid= 22154141|doi=10.1016/j.ejop.2011.10.001 }}</ref> |
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<ref name="Lasek-Nesselquist-2001">{{cite journal|vauthors=Lasek-Nesselquist E, Katz LA|title=Phylogenetic position of Sorogena stoianovitchae and relationships within the class Colpodea (Ciliophora) based on SSU rDNA sequences|journal=Journal of Eukaryotic Microbiology|date=September-October 2001|volume=48|issue=5|pages=604–607|pmid=11596926|doi=10.1111/j.1550-7408.2001.tb00197.x}}</ref> |
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<ref name="Schaap-2006">{{cite journal|vauthors=Schaap P, Winckler T, Nelson M, Alvarez-Curto E, Elgie B, Hagiwara H, etal.|title=Molecular phylogeny and evolution of morphology in the social amoebas|journal=Science|date=October 2006|volume=314|pages=661–663|pmid=17068267|pmc=2173941|doi=10.1126/science.1130670|doi-access=free}}</ref> |
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Revision as of 18:14, 7 June 2023
| Syssomonas | |
|---|---|
| |
| SEM image of Syssomonas. ac = acroneme, fl = flagellum | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Clade: | Pluriformea |
| Class: | Corallochytrea |
| Order: | Corallochytrida |
| Family: | Syssomonadidae |
| Genus: | Syssomonas |
| Species: | S. multiformis
|
| Binomial name | |
| Syssomonas multiformis Tikhonenkov, Hehenberger, Mylnikov & Keeling 2017[1]
| |
| Type strain | |
| Colp-12 MI-PR205[a] | |
Syssomonas is a monotypic genus of unicellular flagellated protists containing the species Syssomonas multiformis. It is a lineage of Holozoa, a clade containing animals and their closest unicellular relatives. It lives in freshwater habitats and has a complex life cycle with amoeboid and flagellated phases.[1][2]
Life cycle
Syssomonas multiformis is a species of unicellular protists with naked cells (lacking any shell or scales) and a large variety of life forms during their highly complex life cycle. These forms include: round flagellate cells (7–14 μm in diameter) with one posterior flagellum, amoeboflagellate cells, amoeboid non-flagellar cells, and spherical cysts. They can also form clusters of multiple cells.[1][2]
Unicellular stages: flagellar, amoeboid and cyst
In the uniflagellar swimming stage, the most common stage of the cycle, the cells of Syssomonas resemble a typical opisthokont cell, reminiscent of animal sperm cells or chytrid zoospores. The flagellum is smooth and emerges from the middle-lateral point of the cell, turns back, and directs backwards during swimming. While swimming, the fast beating of the flagellum can create the appearance of two flagella. The swimming cells rotate, and can suddenly stop and change direction of the movement. Solitary cells can attach temporarily to a substrate through the anterior part of the cell body, and produce water flow by rapid flagellar beating, resembling choanoflagellates or choanocytes from sponges. Floating cells move downwards to transform into amoeboflagellates by generating wide lobopodia and thin short filopodia, and slowing the flagellar beating. The amoeboflagellates can crawl along the substrate through their anterior lobopodia.[2]
The amoeboflagellate stages of Syssomonas can lose the flagellum by three different ways: discarding it abruptly, retracting it into the cell when stretched out, or convolve under the cell and then retract into the cell as a spiral. As a result they become the amoeboid stage, which produces thin short filopodia and sometimes have two contractile vacuoles. Both amoebae and amoeboflagellates can turn back into flagellates.[2]
The amoeboid stage can retract its filopodia and become a round cyst, in which palintomic cell division (i.e. rapid cell divisions without cytoplasmic growth in between, a characteristic of animal embryonic cleavage)[3] can occur, generating 2, 4, 8 or 16 flagellated cells that are released from inside the cyst.[2]
Aggregative multicellular stages
Cells of Syssomonas can merge partially and form temporary aggregations of about 3–10 cells, usually shapeless and observed near the bottom of the water column. They can also aggregate by joining only flagellated cells together, with their flagella directed outwards, resembling the rosette-like colonies of choanoflagellates. Both aggregations break up easily, and their cell membranes are not fused.[2]
In solid cultures, solitary cells can sometimes merge completely at the bottom of the Petri dish into a syncytium-like or pseudoplasmodium structure, in which the nuclei do not merge. From these syncytia, budding of daughter cells occurs. This phenomenon of budding from syncytia has not been observed in any other eukaryotes, although the formation of multinucleated cells as a result of aggregation of multiple cells is known in other protist lineages (dictyostelids in Eumycetozoa, Copromyxa in Tubulinea,[4] acrasids in Excavata,[5] Sorogena in Alveolata,[6] Sorodiplophrys in Stramenopiles, Guttulinopsis in Rhizaria,[7] and Fonticula alba within the opisthokonts).[8] The transition from an amoeboid filopodial stage to an aggregative stage is also observed in another holozoan, Capsaspora owczarzaki. Syncytia are not unusual in animals either; the cytoplasm of glass sponges, teguments of flatworms, and the skeletal muscles and placenta of mammals are syncytial structures.[2]
The merging of cells in Syssomonas attracts, again, likely by chemical signaling, other nearby cells that actively swim and try to attach to the aggregates. This appears to be the only method by which aggregates grow, as opposed to cell division.[2]
Ecology
Syssomonas multiformis was isolated from a freshwater pool in Vietnam. The organism can survive temperatures ranging from 5 to 36 °C. It feeds on the cytoplasmic content of other eukaryotes of similar size, which is an unusual trait among unicellular holozoans. In particular, it is a predator of heterotrophic chrysomonads and bodonids (e.g. Parabodo caudatus and Spumella species).[2] They can also engulf bacteria and small detritus, in a similar manner to choanoflagellates.[1]
In contrast to many other eukaryotic protists, Syssomonas cells do not possess any extrusive organelles for hunting. Instead, they attach to the prey cell and sucks out their cytoplasm without ingesting the cell membrane. They feed better on inactive, slow or dead cells or cysts. Likely by chemical signaling, after one cell attaches to the prey, many other Syssomonas cells become attracted to the same prey cell and try to attach to it. Several cells can suck out the cytoplasm of the same prey cell jointly.[2]
They use short pseudopodia to feed on clusters of bacteria. Afterwards, they form a large food vacuole at the posterior cell end. However, bacteria alone are not sufficient nutrition for Syssomonas: without any eukaryotic prey, their cells die or form resting cysts.[2]
Evolution
As a lineage of Holozoa, Syssomonas is one of many protist groups closely related to animals and is therefore a subject of research in the search for the origin of animal multicellularity.[1]
The first phylogenomic analyses including Syssomonas recovered the genus as the sister taxon of Corallochytrium. Together, they compose the clade Pluriformea, which was recovered as the sister taxon of Filozoa.[1] An alternative hypothesis places Pluriformea as the sister group of Ichthyosporea in a clade known as Teretosporea.[2]
Notes
- ^ Deposited in the Marine Invertebrate Collection, Beaty Biodiversity Museum, University of British Columbia[1]
References
- ^ a b c d e f g Hehenberger E, Tikhonenkov DV, Kolisko M, del Campo J, Esaulov AS, Mylnikov AP, Keeling PJ (2017). "Novel Predators Reshape Holozoan Phylogeny and Reveal the Presence of a Two-Component Signaling System in the Ancestor of Animals". Current Biology. 27 (13): 2043–2050.e6. doi:10.1016/j.cub.2017.06.006.
- ^ a b c d e f g h i j k l Tikhonenkov DV, Hehenberger E, Esaulov AS, Belyakova OI, Mazei YA, Mylnikov AP, Keeling PJ (2020). "Insights into the origin of metazoan multicellularity from predatory unicellular relatives of animals". BMC Biology. 18: 39. doi:10.1186/s12915-020-0762-1.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Chen L, Xiao S, Pang K, Zhou C, Yuan X (September 2014). "Cell differentiation and germ–soma separation in Ediacaran animal embryo-like fossils". Nature. 516: 238–241. doi:10.1038/nature13766.
- ^ Brown MW, Silberman JD, Spiegel FW (April 2011). ""Slime molds" among the Tubulinea (Amoebozoa): molecular systematics and taxonomy of Copromyxa". Protist. 162 (2): 277–287. doi:10.1016/j.protis.2010.09.003.
- ^ Brown MW, Silberman JD, Spiegel FW (May 2012). "A contemporary evaluation of the acrasids (Acrasidae, Heterolobosea, Excavata)". European Journal of Protistology. 48 (2): 103–123. doi:10.1016/j.ejop.2011.10.001. PMID 22154141.
- ^ Lasek-Nesselquist E, Katz LA (September–October 2001). "Phylogenetic position of Sorogena stoianovitchae and relationships within the class Colpodea (Ciliophora) based on SSU rDNA sequences". Journal of Eukaryotic Microbiology. 48 (5): 604–607. doi:10.1111/j.1550-7408.2001.tb00197.x. PMID 11596926.
{{cite journal}}: CS1 maint: date format (link) - ^ Brown MW, Kolisko M, Silberman JD, Roger AJ (2012). "Aggregative Multicellularity Evolved Independently in the Eukaryotic Supergroup Rhizaria". Current Biology. 22 (12): 1123–1127. doi:10.1016/j.cub.2012.04.021. PMID 22608512. S2CID 17510471.
- ^ Schaap P, Winckler T, Nelson M, Alvarez-Curto E, Elgie B, Hagiwara H, et al. (October 2006). "Molecular phylogeny and evolution of morphology in the social amoebas". Science. 314: 661–663. doi:10.1126/science.1130670. PMC 2173941. PMID 17068267.