Proterospongia
Encyclopedia
Proterospongia is a genus
of choanoflagellate
, notable for its formation of colonies. As a colony-forming choanoflagellate
, Proterospongia is of interest to scientists studying the mechanisms of intercellular signaling and adhesion present prior to the origin of animal
s.
cell structure characterized by a cell body 5-10μm in diameter with a 20-30μm apical flagellum
surrounded by a collar of 15-25 actin-filled microvilli. The flagellum
propels swimming cells through the water column and creates water currents through the microvilli, which trap foodstuff such as bacteria and detritus.The arrangement of organelles in Proterospongia appears consistent with other choanoflagellates and is characterized by an anterior dictyosome under the flagellar base, a central nucleus, peripheral mitochondria and a posterior food vacuole.
As a member of the Codonosigidae
family, Proterospongia have only a fine investment that is indistinct by light microscopy or completely lack an outer-covering. Proterospongia species are distinguished by colony morphology, which vary from simple chains of cells to striking astral assemblages. Colonies having extra cellular jelly or mucilage have been described by Kent, Lackey, and Leadbeater; however the composition of this substance is unknown. Kent also described a Proterospongia species containing two types of cells embedded in mucilage; however, this is the only account of such a species and it has been suggested that the observed amoeboid cells were actually posterior tentacles that are present on some choanoflagellates.
have been described, only choanojuncta has a described life history. Based on this description, Proterospongia alternates between colonial and swimming and adherent solitary states. Leadbeater’s 1983 description resulted in the consolidation of Choanocea perplexea and Proterospongia choanojuncta species into Proterospongia choanojuncta. Additional studies of solitary and colonial species
may result in further species
consolidation.
choanoflagellates based on the physical appearance of individual cells and the morphology of the colony. First described by Kent in Manual of the Infusoria (1880-1882), there are six described species
of Proterospongia and the colony structure varies between species
. The members of Proterospongia genus
remain to be classified in a phylogenetic framework.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of choanoflagellate
Choanoflagellate
The choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals...
, notable for its formation of colonies. As a colony-forming choanoflagellate
Choanoflagellate
The choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals...
, Proterospongia is of interest to scientists studying the mechanisms of intercellular signaling and adhesion present prior to the origin of animal
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
s.
Physical Characteristics
Members of Proterospongia have the typical choanoflagellateChoanoflagellate
The choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals...
cell structure characterized by a cell body 5-10μm in diameter with a 20-30μm apical flagellum
Flagellum
A flagellum is a tail-like projection that protrudes from the cell body of certain prokaryotic and eukaryotic cells, and plays the dual role of locomotion and sense organ, being sensitive to chemicals and temperatures outside the cell. There are some notable differences between prokaryotic and...
surrounded by a collar of 15-25 actin-filled microvilli. The flagellum
Flagellum
A flagellum is a tail-like projection that protrudes from the cell body of certain prokaryotic and eukaryotic cells, and plays the dual role of locomotion and sense organ, being sensitive to chemicals and temperatures outside the cell. There are some notable differences between prokaryotic and...
propels swimming cells through the water column and creates water currents through the microvilli, which trap foodstuff such as bacteria and detritus.The arrangement of organelles in Proterospongia appears consistent with other choanoflagellates and is characterized by an anterior dictyosome under the flagellar base, a central nucleus, peripheral mitochondria and a posterior food vacuole.
As a member of the Codonosigidae
Codonosigidae
Codonosigidae is a Choanoflagellate family....
family, Proterospongia have only a fine investment that is indistinct by light microscopy or completely lack an outer-covering. Proterospongia species are distinguished by colony morphology, which vary from simple chains of cells to striking astral assemblages. Colonies having extra cellular jelly or mucilage have been described by Kent, Lackey, and Leadbeater; however the composition of this substance is unknown. Kent also described a Proterospongia species containing two types of cells embedded in mucilage; however, this is the only account of such a species and it has been suggested that the observed amoeboid cells were actually posterior tentacles that are present on some choanoflagellates.
Life History
Although several Proterospongia speciesSpecies
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
have been described, only choanojuncta has a described life history. Based on this description, Proterospongia alternates between colonial and swimming and adherent solitary states. Leadbeater’s 1983 description resulted in the consolidation of Choanocea perplexea and Proterospongia choanojuncta species into Proterospongia choanojuncta. Additional studies of solitary and colonial species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
may result in further species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
consolidation.
Classification
Proterospongia is a taxonomic classification of colonial CodonosigidaeCodonosigidae
Codonosigidae is a Choanoflagellate family....
choanoflagellates based on the physical appearance of individual cells and the morphology of the colony. First described by Kent in Manual of the Infusoria (1880-1882), there are six described species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of Proterospongia and the colony structure varies between species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
. The members of Proterospongia genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
remain to be classified in a phylogenetic framework.
Additional References
- James, T. Y., F. Kauff, C. L. Schoch, et al. mult. 2006. Reconstructing the early evolution of Fungi using a six-gene phylogeny. Nature 443:818-22.
- Lang, B. F., C. O'Kelly, T. Nerad, M. W. Gray, and G. Burger. 2002. The closest unicellular relatives of animals. Curr Biol 12:1773-8.
- Philippe, H, Snell, EA, Bapteste, E, Lopez, P, Holland, PWH, and D Casane. 2004. Phylogenomics of eukaryotes: the impact of missing data on alignments. Molecular Biology and Evolution. 21(9):123-135.
- Snell, EA, Furlong, RF, and PWH Holland. 2001. Hsp70 sequences indicate that choanoflagellates are closely related to animals. Current Biology. 11:967-970.