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Proto-mitochondrion
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, there is no definitive evidence as to which alphaproteobacterial group the proto-mitochondrion emerged from. 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 ribosomal RNA sequences. Metabolism Toni Gabaldón and Martijn Huynen (2003) reconstru ... [...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] |
Mitochondria
A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double 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'' was coined by Carl Benda in 1898. The mitochondrion is popularly nicknamed the "powerhouse of the cell", a phrase coined by Philip Siekevitz in a 1957 article of the same name. Some cells in some multicellular organisms lack mitochondria (for example, mature mammalian red blood cells). A large number of unicellular organisms, such as microsporidia, parabasalids and diplomonads, have reduced or transformed their mitochondria into other structures. One eukaryote, ''Monocercomonoides'', is known to have completely lost its mitochondria, and one multicellular organism, ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symbiogenesis
Symbiogenesis (endosymbiotic theory, or serial endosymbiotic theory,) is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. The theory holds that mitochondria, plastids such as chloroplasts, and possibly other organelles of eukaryotic cells are descended from formerly free-living prokaryotes (more closely related to the Bacteria than to the Archaea) taken one inside the other in endosymbiosis. Mitochondria appear to be phylogenetically related to Rickettsiales bacteria, while chloroplasts are thought to be related to cyanobacteria. The idea that chloroplasts were originally independent organisms that merged into a symbiotic relationship with other one-celled organisms dates back to the 19th century, when it was espoused by researchers such as Andreas Schimper. The endosymbiotic theory was articulated in 1905 and 1910 by the Russian botanist Konstantin Mereschkowski, and advanced and substantiated with microbiological evidenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, Hot spring, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the nitrogen fixation, fixation of nitrogen from the Earth's atmosphere, atmosphere. The nutrient cycle includes the decomposition of cadaver, dead bodies; bacteria are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelagibacter
"''Candidatus'' Pelagibacter", with the single species "''Ca.'' P. communis", was isolated in 2002 and given a specific name, although it has not yet been described as required by the bacteriological code. It is an abundant member of the SAR11 clade in the phylum ''Alphaproteobacteria''. SAR11 members are highly dominant organisms found in both salt and fresh water worldwide and were originally known only from their rRNA genes, first identified in the Sargasso Sea in 1990 by Stephen Giovannoni's laboratory at Oregon State University and later found in oceans worldwide. "''Ca.'' P. communis" and its relatives may be the most abundant organisms in the ocean, and quite possibly the most abundant bacteria in the entire world. It can make up about 25% of all microbial plankton cells, and in the summer they may account for approximately half the cells present in temperate ocean surface water. The total abundance of "''Ca.'' P. communis" and relatives is estimated to be about 2 � ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holosporales
The ''Holosporales'' are an order of bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am .... References Alphaproteobacteria Bacteria orders {{alphaproteobacteria-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rickettsidae
Alphaproteobacteria 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 and some of its intracellular parasitic members lack peptidoglycan and are consequently gram variable. Characteristics The Alphaproteobacteria are a diverse taxon and comprises 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 that was engulfed by the eukaryotic ancestor and gave rise to the mitochondria, which are organelles in eukaryotic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelagibacterales
The Pelagibacterales are an order in the Alphaproteobacteria composed of free-living marine bacteria that make up roughly one in three cells at the ocean's surface. Overall, members of the ''Pelagibacterales'' are estimated to make up between a quarter and a half of all prokaryotic cells in the ocean. Initially, this taxon was known solely by metagenomic data and was known as the SAR11 clade. It was first placed in the Rickettsiales, but was later raised to the rank of order, and then placed as sister order to the Rickettsiales in the subclass Rickettsidae. It includes the highly abundant marine species ''Pelagibacter ubique''. Bacteria in this order are unusually small. Due to their small genome size and limited metabolic function, ''Pelagibacterales'' have become a model organism for ' streamlining theory'. ''P. ubique'' and related species are oligotrophs (scavengers) and feed on dissolved organic carbon and nitrogen. They are unable to fix carbon or nitrogen, but can perf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelagibacteraceae
The Pelagibacteraceae are a family in the Alphaproteobacteria composed of free-living marine bacteria Marine prokaryotes are marine bacteria and marine archaea. They are defined by their habitat as prokaryotes that live in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. All cellular .... References Alphaproteobacteria {{alphaproteobacteria-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaplasma
''Anaplasma'' is a genus of bacteria of the alphaproteobacterial order Rickettsiales, family Anaplasmataceae. ''Anaplasma'' species reside in host blood cells and lead to the disease anaplasmosis. The disease most commonly occurs in areas where competent tick vectors are indigenous, including tropical and semitropical areas of the world for intraerythrocytic ''Anaplasma'' spp.Anaplasmas reviewed and published by , accessed 10 October 2011. ''Anaplasma'' species are biologically transmitted by Ixodes deer-tick vectors, and the prototypical species, ''A. marginale,'' can be mechanically transmitted by biting flies and iatrogenically with blood-contaminat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaplasmataceae
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] |
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 com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
