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Proterospongia
''Proterospongia'' is a genus of single-celled aquatic organisms which form colonies. It belongs to the choanoflagellate class. As a colony-forming choanoflagellate, ''Proterospongia'' is of interest to scientists studying the mechanisms of intercellular signaling and adhesion present before animals appeared. King, N. The Unicellular Ancestry of Animal Development. Developmental Cell (2004) 7:313-325King, N. and S. B. Carroll. 2001. A receptor tyrosine kinase from choanoflagellates: molecular insights into early animal evolution. Proc Natl Acad Sci U S A 98:15032-7. Physical characteristics Members of ''Proterospongia'' have the typical choanoflagellate 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.Leadbeater, B.S.C.; Thomsen H.A. Order Choanoflagellida. The Illustrated Guide to the Protozoa, second edition, (2000) pp. 14-37.Leadbeater, B.S.C. Life-History and Ultrastructure o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 interconnected microvilli at the base of a flagellum. Choanoflagellates are capable of both asexual and sexual reproduction. They have a distinctive cell morphology characterized by an ovoid or spherical cell body 3–10 µm in diameter with a single apical flagellum surrounded by a collar of 30–40 microvilli (see figure). Movement of the flagellum creates water currents that can propel free-swimming choanoflagellates through the water column and trap bacteria and detritus against the collar of microvilli, where these foodstuffs are engulfed. This feeding provides a critical link within the global carbon cycle, linking trophic levels. In addition to their critical ecological roles, choanoflagellates are of particular interest to evolutionary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Choanoflagellatea
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 interconnected microvilli at the base of a flagellum. Choanoflagellates are capable of both asexual and sexual reproduction. They have a distinctive cell morphology characterized by an ovoid or spherical cell body 3–10 µm in diameter with a single apical flagellum surrounded by a collar of 30–40 microvilli (see figure). Movement of the flagellum creates water currents that can propel free-swimming choanoflagellates through the water column and trap bacteria and detritus against the collar of microvilli, where these foodstuffs are engulfed. This feeding provides a critical link within the global carbon cycle, linking trophic levels. In addition to their critical ecological roles, choanoflagellates are of particular interest to evolutionary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holozoa
Holozoa is a group of organisms that includes animals and their closest single-celled relatives, but excludes fungi. ''Holozoa'' is also an old name for the tunicate genus ''Distaplia''.'' Because Holozoa is a clade including all organisms more closely related to animals than to fungi, some authors prefer it to recognizing paraphyletic groups that mostly consists of Holozoa minus animals. Perhaps the best-known holozoans, apart from animals, are the choanoflagellates, which strongly resemble the collar cells of sponges, and so were theorized to be related to sponges even in the 19th century. ''Proterospongia'' is an example of a colonial choanoflagellate that may shed light on the origin of sponges. The affinities of the other single-celled holozoans only began to be recognized in the 1990s. The sub-classification Ichthyosporea or Mesomycetozoea contains a number of mostly parasitic species. The amoeboid genera ''Ministeria'' and ''Capsaspora'' may be united in a group call ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Codonosigidae
Codonosigidae were a 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 ... family. In the newest taxonomy the family Codonsigidae is replaced by the Salpingoecidae. References Opisthokont families Choanoflagellatea {{Holozoa-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryota
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. Bacteria and Archaea (both prokaryotes) make up the other two domains. The eukaryotes are usually now regarded as having emerged in the Archaea or as a sister of the Asgard archaea. This implies that there are only two domains of life, Bacteria and Archaea, with eukaryotes incorporated among archaea. Eukaryotes represent a small minority of the number of organisms, but, due to their generally much larger size, their collective global biomass is estimated to be about equal to that of prokaryotes. Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the Proterozoic eon, likely as flagellated phagotrophs. Their name comes from the Greek εὖ (''eu'', "well" or "good") and κάρυον (''karyon'', "nut" or "kernel"). E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. '' Panthera leo'' (lion) and '' Panthera onca'' (jaguar) are two species within the genus '' Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. phylogenetic analysis should cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colony (biology)
In biology, a colony is composed of two or more conspecific individuals living in close association with, or connected to, one another. This association is usually for mutual benefit such as stronger defense or the ability to attack bigger prey. Colonies can form in various shapes and ways depending on the organism involved. For instance, the bacterial colony is a cluster of identical cells (clones). These colonies often form and grow on the surface of (or within) a solid medium, usually derived from a single parent cell. Colonies, in the context of development, may be composed of two or more unitary (or solitary) organisms or be modular organisms. Unitary organisms have determinate development (set life stages) from zygote to adult form and individuals or groups of individuals (colonies) are visually distinct. Modular organisms have indeterminate growth forms (life stages not set) through repeated iteration of genetically identical modules (or individuals), and it can be diffi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicole King
Nicole King (born 1970) is an American biologist and faculty member at the University of California, Berkeley in molecular and cell biology and integrative biology. She was awarded a MacArthur Fellowship in 2005. She has been an investigator with the Howard Hughes Medical Institute (HHMI) since 2013. King studies the evolution of multicellularity and choanoflagellates. The goal of her work is to reconstruct how multicellular animals evolved from single-cell organisms. Professional contributions King identified choanoflagellates as key organisms to answer questions about the origin of multicellularity. Prior to her work, it was unclear whether choanoflagellates or fungi were the closest outgroup to multicellular animals (also called "metazoans"). King's comparative genomics work in collaboration with Sean Carroll helped to elucidate the evolutionary "tree of life." In addition, work by King and colleagues showed that choanoflagellates possess several protein-coding genes that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sean B
Sean, also spelled Seán or Séan in Irish English, is a male given name of Irish origin. It comes from the Irish versions of the Biblical Hebrew name ''Yohanan'' (), Seán (anglicized as ''Shaun/ Shawn/ Shon'') and Séan (Ulster variant; anglicized ''Shane/Shayne''), rendered ''John'' in English and Johannes/Johann/Johan in other Germanic languages. The Norman French ''Jehan'' (see ''Jean'') is another version. For notable people named Sean, refer to List of people named Sean. Origin The name was adopted into the Irish language most likely from ''Jean'', the French variant of the Hebrew name ''Yohanan''. As Gaelic has no letter (derived from ; English also lacked until the late 17th Century, with ''John'' previously been spelt ''Iohn'') so it is substituted by , as was the normal Gaelic practice for adapting Biblical names that contain in other languages (''Sine''/''Siobhàn'' for ''Joan/Jane/Anne/Anna''; ''Seonaid''/''Sinéad'' for ''Janet''; ''Seumas''/''Séamus'' for ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flagellum
A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have from one to many flagella. A gram-negative bacterium '' Helicobacter pylori'' for example uses its multiple flagella to propel itself through the mucus lining to reach the stomach epithelium, where it may cause a gastric ulcer to develop. In some bacteria the flagellum can also function as a sensory organelle, being sensitive to wetness outside the cell. Across the three domains of Bacteria, Archaea, and Eukaryota the flagellum has a different structure, protein composition, and mechanism of propulsion but shares the same function of providing motility. The Latin word means " whip" to describe its lash-like swimming motion. The flagellum in archaea is called the archaellum to note its difference from the bacterial flagellum. Euk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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