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Rickettsiales
The Rickettsiales, informally called rickettsias, are an order of small Alphaproteobacteria. They are obligate intracellular parasites, and some are notable pathogens, including '' Rickettsia'', which causes a variety of diseases in humans, and '' Ehrlichia'', which causes diseases in livestock. Another genus of well-known Rickettsiales is the '' Wolbachia'', which infect about two-thirds of all arthropods and nearly all filarial nematodes. Genetic studies support the endosymbiotic theory according to which mitochondria and related organelles developed from members of this group. The Rickettsiales are difficult to culture, as they rely on living eukaryotic host cells for their survival. Rickettsiales phylogeny The Rickettsiales further consist of three known families, the Rickettsiaceae, the Midichloriaceae, and the Ehrlichiaceae. Most studies also support the inclusion of the Holosporaceae, but one study has challenged this view. In that alternative, the Holosporaceae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alphaproteobacteria
''Alphaproteobacteria'' or ''α-proteobacteria'', also called ''α-Purple bacteria'' in earlier literature, is a class of bacteria in the phylum '' Pseudomonadota'' (formerly "Proteobacteria"). The '' Magnetococcales'' and '' Mariprofundales'' are considered basal or sister to the ''Alphaproteobacteria''. The ''Alphaproteobacteria'' are highly diverse and possess few commonalities, but nevertheless share a common ancestor. Like all ''Proteobacteria'', its members are gram-negative, although some of its intracellular parasitic members lack peptidoglycan and are consequently gram variable. Characteristics The ''Alphaproteobacteria'' are a diverse taxon and comprise several phototrophic genera, several genera metabolising C1-compounds (e.g. ''Methylobacterium'' spp.), symbionts of plants (e.g. '' Rhizobium'' spp.), endosymbionts of arthropods ('' Wolbachia'') and intracellular pathogens (e.g. '' Rickettsia''). Moreover, the class is sister to the protomitochondrion, the bacterium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protomitochondrion
The proto-mitochondrion is the hypothetical ancestral bacterial endosymbiont from which all mitochondria in eukaryotes are thought to descend, after an episode of symbiogenesis which created the aerobic eukaryotes. Phylogeny The phylogenetic analyses of the few genes that are still encoded in the genomes of modern mitochondria suggest an alphaproteobacterial origin for this endosymbiont, in an ancient episode of symbiogenesis early in the history of the eukaryotes. Although the order ''Rickettsiales'' has been proposed as the alphaproteobacterial sister-group of mitochondria, no definitive evidence pinpoints the alphaproteobacterial group from which the proto-mitochondrion emerged, and some contradictory evidence, especially in the early, sparse genome samplings. Martijn ''et al'' found mitochondria are a possible sister-group to all other alphaproteobacteria. The phylogenetic tree of the Rickettsidae has been inferred by Ferla ''et al.'' from the comparison of 16S + 23S ribo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Midichloriaceae
"''Candidatus''" Midichloriaceae is a family of bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ..., included in the order Rickettsiales. No member of this family has been cultured in the laboratory, so the entire family has been given the status '' candidatus''. References Rickettsiales {{alphaproteobacteria-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rickettsia
''Rickettsia'' is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long). The genus was named after Howard Taylor Ricketts in honor of his pioneering work on tick-borne spotted fever. Properly, ''Rickettsia'' is the name of a single genus, but the informal term "rickettsia", plural "rickettsias," usually not capitalised, commonly applies to any members of the order Rickettsiales. Being obligate intracellular bacteria, rickettsias depend on entry, growth, and replication within the cytoplasm of living eukaryotic host cells (typically endothelial cells). Accordingly, ''Rickettsia'' species cannot grow in artificial nutrient culture; they must be grown either in tissue or embryo cultures. Mostly chicken embryos are used, following a method developed by Ernest William Goodpasture and his colleagues at Vanderbilt University i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ehrlichia
''Ehrlichia'' is a genus of Rickettsiales bacteria that are transmitted to vertebrates by ticks. These bacteria cause the disease ehrlichiosis, which is considered zoonotic, because the main reservoirs for the disease are animals. ''Ehrlichia'' species are obligately intracellular pathogens and are transported between cells through the host cell filopodia during initial stages of infection, whereas in the final stages of infection, the pathogen ruptures the host cell membrane. History The genus ''Ehrlichia'' is named after German microbiologist Paul Ehrlich. The first ehrlichial disease was recognized in South Africa during the 19th century. Its tick-borne nature was determined in 1900. The organism itself was demonstrated in 1925 when it was recognized to be a ''Rickettsia''. It was initially named ''Rickettsia ruminantium'', and is currently named '' Ehrlichia ruminantium''. In 1945, an "infection and treatment" method for livestock was developed. This is still the only comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ehrlichiaceae
The Ehrlichiaceae are a family of bacteria, included in the order Rickettsiales The Rickettsiales, informally called rickettsias, are an order of small Alphaproteobacteria. They are obligate intracellular parasites, and some are notable pathogens, including '' Rickettsia'', which causes a variety of diseases in humans, and .... References External links * Rickettsiales Bacteria families {{alphaproteobacteria-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rickettsiaceae
The Rickettsiaceae are a family of bacteria. The genus ''Rickettsia'' is the most prominent genus within the family. The bacteria that eventually formed the mitochondrion (an organelle in eukaryotic cells) is believed to have originated from this family. Most human pathogens in this family are in genus ''Rickettsia''. They spend part of their lifecycle in the bodies of arthropods such as ticks or lice, and are then transmitted to humans or other mammals by the bite of the arthropod. It contains Gram-negative bacteria, very sensitive to environmental exposure, thus is adapted to obligate intracellular infection. '' Rickettsia rickettsii'' is considered the prototypical infectious organism in the group. Genomics Comparative genomic analysis has identified three proteins, RP030, RP187 and RP192, which are uniquely found in members of the family Rickettsiaceae and serve as molecular markers for this family. In addition, conserved signature indels in a number of proteins including ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holosporaceae
The Holosporaceae are a family of bacteria. The member ''Holospora'' is an intracellular parasite found in the unicellular protozoa ''Paramecium ''Paramecium'' ( , , plural "paramecia" only when used as a Common name, vernacular name) is a genus of eukaryotic, unicellular ciliates, widespread in freshwater, brackish, and Ocean, marine environments. Paramecia are often abundant in stagna ...''. Genome Draft genome sequences are available for three ''Holospora'' species and ''Odyssella thessalonicensis'' . References External links HolosporaceaeJ.P. Euzéby: List of Prokaryotic names with Standing in Nomenclature Rickettsiales {{alphaproteobacteria-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wolbachia
''Wolbachia'' is a genus of gram-negative bacteria infecting many species of arthropods and filarial nematodes. The symbiotic relationship ranges from parasitism to obligate mutualism. It is one of the most common parasitic microbes of arthropods, and is possibly the most widespread reproductive parasite bacterium in the biosphere. Its interactions with hosts are complex and highly diverse across different host species. Some host species cannot reproduce, or even survive, without ''Wolbachia'' colonisation. One study concluded that more than 16% of neotropical insect species carry bacteria of this genus, and as many as 25 to 70% of all insect species are estimated to be potential hosts. History The first organism classified as ''Wolbachia'' was discovered in 1924 by Marshall Hertig and Simeon Burt Wolbach in the common house mosquito. They described it as "a somewhat pleomorphic, rodlike, Gram-negative, intracellular organism hatapparently infects only the ovaries and te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitochondrion
A mitochondrion () is an organelle found in the cell (biology), cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used throughout the cell as a source of chemical energy. They were discovered by Albert von Kölliker in 1857 in the voluntary muscles of insects. The term ''mitochondrion'', meaning a thread-like granule, was coined by Carl Benda in 1898. The mitochondrion is popularly nicknamed the "powerhouse of the cell", a phrase popularized by Philip Siekevitz in a 1957 ''Scientific American'' article of the same name. Some cells in some multicellular organisms lack mitochondria (for example, mature mammalian red blood cells). The multicellular animal ''Henneguya zschokkei, Henneguya salminicola'' is known to have retained mitochondrion-related organelles despite a complete loss of their mitochondrial genome. A large number ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rickettsia Rickettsii
''Rickettsia rickettsii'' is a Gram-negative, intracellular, cocco-bacillus bacterium that was first discovered in 1902. Having a reduced genome, the bacterium harvests nutrients from its host cell to carry out respiration, making it an organo-heterotroph. Maintenance of its genome is carried out through vertical gene transfer where specialization of the bacterium allows it to shuttle host sugars directly into its TCA cycle. Other characteristics of the bacteria include membrane proteins that are useful in the identification of ''R. rickettsii'' strains and useful in targeting from antibiotics. A capsule encircling the bacterium allows for attachment to host cells and additionally acts as a defense mechanism for resisting phagocytosis. Varying strains of ''R. rickettsii'' have different genotypes and phenotypes that alter the pathogenicity, virulence, and the appearance of the bacteria. ''R. rickettsii'' is the causative agent of Rocky Mountain Spotted Fever and is transferre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
