''Salpingoeca rosetta'' is a species of

Choanoflagellate The choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals. Choanoflagellates are collared flagellates, having a funnel shaped collar of interconne ...

s in the family

Salpingoecidae Salpingoecidae is a family of Choanoflagellate The choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals. Choanoflagellates are collared flagell ...

. It is a rare marine

eukaryote Eukaryotes () are organisms whose cells have a 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 three domains of life. Bacter ...

consisting of a number of cells embedded in a jelly-like matrix. This organism demonstrates a very primitive level of

cell differentiation Cellular differentiation is the process in which a stem cell alters from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a multicellular ...

and specialization. This is seen with flagellated cells and their collar structures that move the cell colony through the water.
Similar low level

cellular differentiation Cellular differentiation is the process in which a stem cell alters from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a multicellular ...

and specification can also be seen in sponges. They also have collar cells (also called

choanocytes Choanocytes (also known as "collar cells") are cells that line the interior of asconoid, syconoid and leuconoid body types of sponges that contain a central flagellum, or ''cilium,'' surrounded by a collar of microvilli which are connected by a ...

due to their similarities to choanoflaggellates) and amoeboid cells arranged in a gelatinous matrix.
Unlike ''S. rosetta'',

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate throu ...

s also have other cell-types that can perform different functions. Also, the collar cells of sponges beat within canals in the sponge body, whereas Salpingoeca rosetta’s collar cells reside on the inside and it lacks internal canals. Despite these minor differences, there is strong evidence that Proterospongia and Metazoa are highly related. Its genome has been studied as a model for Pre

metazoan Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in ...

evolution. The genome is 55 megabases in size. Homologs of cell adhesion, neuropeptide and glycosphingolipid metabolism genes are present in the genome. Dayel Protero Colonies inset

Reproduction cycle

''S. rosetta'' has a sexual cycle during which it transitions between haploid and diploid stages. When nutrients become limiting, haploid cultures of ''S. rosetta'' become diploid. This ploidy shift coincides with mating during which small, flagellated cells fuse with larger flagellated cells. Evidence has also been obtained for historical mating and recombination in ''S. rosetta''. ''S. rosetta'' can be induced to undergo sexual reproduction by the marine bacterium ''

Vibrio fischeri ''Aliivibrio fischeri'' (also called ''Vibrio fischeri'') is a Gram-negative, rod-shaped bacterium found globally in marine environments. This species has bioluminescent properties, and is found predominantly in symbiosis with various marine anim ...

''. A single protein of ''V. fischeri'', EroS, fully recapitulates the aphrodesiac-like activity of living ''V. fischeri''.

Colonial organization

''S. rosetta'' was named for the rosette-shaped colonies formed by its cells. The colonies are held together by adhesion molecules long thought to be found only in

Metazoan Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in ...

organisms. Additionally, recent evidence suggests that a bacterial sulfonolipid, called rosette inducing factor (RIF-1) and produced by '' Algoriphagus machipongonensis'', triggers colony formation in ''S. rosetta''. The effect of RIF-1 on colony formation in ''S. rosetta'' has been suggested as an example of how interactions between bacteria and eukaryotes may have led to multicellularity in the latter.

References

External links

* Choanoflagellatea Protists described in 2011 {{Holozoa-stub