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Jakobea
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, consists of only twenty species at present, and was classified as a group in 1993. There is ongoing research into the mitochondrial genomes of jakobids, which are unusually large and bacteria-like, evidence that jakobids may be important to the evolutionary history of eukaryotes. Molecular phylogenetic evidence suggests strongly that jakobids are most closely related to Heterolobosea (Percolozoa) and Euglenozoa. Structure and Biology Jakobids have two flagella, inserted in the anterior end of the cell, and, like other members of order Excavata, have a ventral feeding groove and associated cytoskeleton support. The posterior flagella has a dorsal vane and is aligned within the ventral groove, where it generates a current that the cell uses f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Excavata
Excavata is a major supergroup of unicellular organisms belonging to the domain Eukaryota. It was first suggested by Simpson and Patterson in 1999 and introduced by Thomas Cavalier-Smith in 2002 as a formal taxon. It contains a variety of free-living and symbiotic forms, and also includes some important parasites of humans, including ''Giardia'' and ''Trichomonas''. Excavates were formerly considered to be included in the now obsolete Protista kingdom. They are classified based on their flagellar structures, and they are considered to be the most basal flagellate lineage. Phylogenomic analyses split the members of Excavata into three different and not all closely related groups: Discobids, Metamonads and Malawimonads. Except for Euglenozoa, they are all non-photosynthetic. Characteristics Most excavates are unicellular, heterotrophic flagellates. Only the Euglenozoa are photosynthetic. In some (particularly anaerobic intestinal parasites), the mitochondria have been greatly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Discoba
Excavata is a major supergroup of unicellular organisms belonging to the domain Eukaryota. It was first suggested by Simpson and Patterson in 1999 and introduced by Thomas Cavalier-Smith in 2002 as a formal taxon. It contains a variety of free-living and symbiotic forms, and also includes some important parasites of humans, including '' Giardia'' and '' Trichomonas''. Excavates were formerly considered to be included in the now obsolete Protista kingdom. They are classified based on their flagellar structures, and they are considered to be the most basal flagellate lineage. Phylogenomic analyses split the members of Excavata into three different and not all closely related groups: Discobids, Metamonads and Malawimonads. Except for Euglenozoa, they are all non-photosynthetic. Characteristics Most excavates are unicellular, heterotrophic flagellates. Only the Euglenozoa are photosynthetic. In some (particularly anaerobic intestinal parasites), the mitochondria have been grea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jakoba
''Jakoba'' is a genus in the taxon Excavata, and currently has a single described species, '' Jakoba libera'' described by Patterson in 1990, and named in honour of Dutch botanist (Algology, Myology and Lichenology) Jakoba Ruinen. (Previously described ''Jakoba incarcerata'' has been renamed ''Andalucia incarcerata'', and '' Jakoba bahamensis'' /'' Jakoba bahamiensis'' is not formally described.) Appearance and characteristics ''Jakoba'' are small bacterivorous zooflagellates ( jakobids) found in marine and hypersaline environments. They are free swimming trophic cells with two flagella and range between five and ten micrometers in length. Cells rotate along their longitudinal axis to allow for swimming in straight lines unless deformation and “squirming” occurs due to compression in debris. During feeding, bacteria are removed from the water column by a current created by the posterior flagellum. This current causes the bacteria to collect in the groove on the right ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jakobidae
''Jakoba'' is a genus in the taxon Excavata, and currently has a single described species, '' Jakoba libera'' described by Patterson in 1990, and named in honour of Dutch botanist (Algology, Myology and Lichenology) Jakoba Ruinen. (Previously described ''Jakoba incarcerata'' has been renamed ''Andalucia incarcerata'', and '' Jakoba bahamensis'' /'' Jakoba bahamiensis'' is not formally described.) Appearance and characteristics ''Jakoba'' are small bacterivorous zooflagellates ( jakobids) found in marine and hypersaline environments. They are free swimming trophic cells with two flagella and range between five and ten micrometers in length. Cells rotate along their longitudinal axis to allow for swimming in straight lines unless deformation and “squirming” occurs due to compression in debris. During feeding, bacteria are removed from the water column by a current created by the posterior flagellum. This current causes the bacteria to collect in the groove on the right ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterolobosea
The Percolozoa are a group of colourless, non-photosynthetic Excavata, including many that can transform between amoeboid, flagellate, and cyst stages. Characteristics Most Percolozoa are found as bacterivores in soil, fresh water and occasionally in the ocean. The only member of this group that is infectious to humans is '' Naegleria fowleri'', the causative agent of the often fatal disease amoebic meningitis. The group is closely related to the Euglenozoa, and share with them the unusual characteristic of having mitochondria with discoid cristae. The presence of a ventral feeding groove in the flagellate stage, as well as other features, suggests that they are part of the Excavata group. The amoeboid stage is roughly cylindrical, typically around 20-40 μm in length. They are traditionally considered lobose amoebae, but are not related to the others, and unlike them, do not form true lobose pseudopods. Instead, they advance by eruptive waves, where hemispherical bulges appe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryotes
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"). Euk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andaluciidae
''Andalucia'' is a genus of jakobids. Classification The morphology of ''Andalucia'' broadly resembles that of other jakobids. Molecular data has not always been conclusive, but recent phylogenomic analyses indicate that ''Andalucia'' is a sister group to the other jakobids, in other words more closely related to them than to the Heterolobosea or Euglenozoa (the other two groups in the Discoba). The α-tubulin gene of ''Andalucia'' more closely resembles that of opisthokonts and diplomonads than its closer relatives, the apparent result of horizontal gene transfer. Species As of 2009, the genus contains two species: * '' A. incarcerata'' was until 2006 known as ''Jakoba incarcerata''. It lives in sulfide-rich sediments, especially marine intertidal ones. Currently it is the type species of the genus ''Stygiella'' Pánek, Táborský & Čepička 2015. * '' A. godoyi'' is a soil heterotroph A heterotroph (; ) is an organism that cannot produce its own food, instead taking ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. 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] |
Reclinomonas
''Reclinomonas'' is a monotypic genus of jakobid eukaryotes containing the single species ''Reclinomonas americana''.Simpson, A. 2008''Reclinomonas'' Flavin & Nerad 1993. ''Reclinomonas americana'' Flavin & Nerad 1993.Version 05. The Tree of Life Web Project. This organism is a single cell up to 12 micrometers wide. It has two flagella. The cell is in a cup-like lorica which has a stem that attaches to a surface. When the cell reproduces, by undergoing binary fission, one of the two newly split cells produces a new lorica for itself. This protozoan can be found in freshwater. This species was the first jakobid to have its mitochondrial genome sequenced. It contains 97 genes, 62 of them code for proteins.Berg, J. M., et al. Biochemistry.' Edition 6. Macmillan. 2010. pg. 505. Other jakobids have been sequenced since, and the data were similar. It has been described as a member of the Excavata Excavata is a major supergroup of unicellular organisms belonging to the domain ... [...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] |
Histiona
''Histiona'' is a genus of Excavata Excavata is a major supergroup of unicellular organisms belonging to the domain Eukaryota. It was first suggested by Simpson and Patterson in 1999 and introduced by Thomas Cavalier-Smith in 2002 as a formal taxon. It contains a variety of free- .... It is a jakobid. References Excavata genera Jakobids {{Excavata-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proceedings Of The National Academy Of Sciences
''Proceedings of the National Academy of Sciences of the United States of America'' (often abbreviated ''PNAS'' or ''PNAS USA'') is a peer-reviewed multidisciplinary scientific journal. It is the official journal of the National Academy of Sciences, published since 1915, and publishes original research, scientific reviews, commentaries, and letters. According to '' Journal Citation Reports'', the journal has a 2021 impact factor of 12.779. ''PNAS'' is the second most cited scientific journal, with more than 1.9 million cumulative citations from 2008 to 2018. In the mass media, ''PNAS'' has been described variously as "prestigious", "sedate", "renowned" and "high impact". ''PNAS'' is a delayed open access journal, with an embargo period of six months that can be bypassed for an author fee (hybrid open access). Since September 2017, open access articles are published under a Creative Commons license. Since January 2019, ''PNAS'' has been online-only, although print issues a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
