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Jakobid
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] |
Stygiella (protist)
''Stygiella'' /ˌstɪ.d͡ʒiˈɛ.lə/ is a genus of free-living marine flagellates belonging to the family Stygiellidae in the jakobids (excavata). The genus currently includes four species, all of which are secondary obligate anaerobes. The species are all unicellular and crescent-shaped.Bernard, C, Simpson, A. G. B. & Patterson, D. J. (2000) Some free-living flagellates (protista) from anoxic habitats, Ophelia, 52:2, 113-142, DOI: 10.1080/00785236.1999.10409422. All members possess hydrogenosomes, a type of acristate mitochondrion-derived organelle (MRO) that produces hydrogen gas as a metabolic product.Leger, M. M., Eme, L., Hug, L. A., & Roger, A. J. (2016). ovel hydrogenosomes in the microaerophilic jakobid ''Stygiella incarcerata'' Molecular Biology and Evolution, 33(9), 2318-2336. Retrieved April 28, 2020. doi: doi.org/10.1093/2Fmolbev/2Fmsw103. Stygiella is a deep-branching lineage within excavates, and hydrogenosome genes sometimes show eubacterium-like mechanisms th ... [...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 ventra ... [...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 ventra ... [...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 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 n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histiona
''Histiona'' is a genus of Excavata. It is a jakobid 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, con .... References Excavata genera Jakobids {{Excavata-stub ... [...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 gre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flagellate
A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and their means of motion. The term presently does not imply any specific relationship or classification of the organisms that possess flagella. However, the term "flagellate" is included in other terms (such as "dinoflagellate" and "choanoflagellata") which are more formally characterized. Form and behavior Flagella in eukaryotes are supported by microtubules in a characteristic arrangement, with nine fused pairs surrounding two central singlets. These arise from a basal body. In some flagellates, flagella direct food into a cytostome or mouth, where food is ingested. Flagella often support hairs, called mastigonemes, or contain rods. Their ultrastructure plays an important role in classifying eukaryotes. Among protoctists and microscopic anima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleolus
The nucleolus (, plural: nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis, which is the synthesis of ribosomes. The nucleolus also participates in the formation of signal recognition particles and plays a role in the cell's response to stress. Nucleoli are made of proteins, DNA and RNA, and form around specific chromosomal regions called nucleolar organizing regions. Malfunction of nucleoli can be the cause of several human conditions called "nucleolopathies" and the nucleolus is being investigated as a target for cancer chemotherapy. History The nucleolus was identified by bright-field microscopy during the 1830s. Little was known about the function of the nucleolus until 1964, when a study of nucleoli by John Gurdon and Donald Brown in the African clawed frog ''Xenopus laevis'' generated increasing interest in the function and detailed structure of the nucleolus. They found that 25% of the frog e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytoskeleton
The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is composed of similar proteins in the various organisms. It is composed of three main components, microfilaments, intermediate filaments and microtubules, and these are all capable of rapid growth or disassembly dependent on the cell's requirements. A multitude of functions can be performed by the cytoskeleton. Its primary function is to give the cell its shape and mechanical resistance to deformation, and through association with extracellular connective tissue and other cells it stabilizes entire tissues. The cytoskeleton can also contract, thereby deforming the cell and the cell's environment and allowing cells to migrate. Moreover, it is involved in many cell signaling pathways and in the uptake of extracellular material ( endocytosis), the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Nucleus
The cell nucleus (pl. nuclei; from Latin or , meaning ''kernel'' or ''seed'') is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm; and the nuclear matrix, a network within the nucleus that adds mechanical support. The cell nucleus contains nearly all of the cell's genome. Nuclear DNA is often organized into multiple chromosomes – long stands of DNA dotted with various proteins, such as histones, that protect and organize the DNA. The genes within these chromosomes are structured in such a way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the cell by regulating gene expres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
