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CPR Group
The candidate phyla radiation (also referred to as CPR group) is a large evolutionary radiation of bacterial lineages whose members are mostly uncultivated and only known from metagenomics and single cell sequencing. They have been described as nanobacteria (not to be confused with non-living nanoparticles of the same name) or ultra-small bacteria due to their reduced size (nanometric) compared to other bacteria. Originally (circa 2016), it has been suggested that CPR represents over 15% of all bacterial diversity and may consist of more than 70 different phyla. However, the Genome Taxonomy Database (2018) based on relative evolutionary divergence found that CPR represents a single phylum, with earlier figures inflated by the rapid evolution of ribosomal proteins. CPR lineages are generally characterized as having small genomes and lacking several biosynthetic pathways and ribosomal proteins. This has led to the speculation that they are likely obligate symbionts. Earlier work ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolutionary Radiation
An evolutionary radiation is an increase in taxonomic diversity that is caused by elevated rates of speciation, that may or may not be associated with an increase in morphological disparity. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment, they are termed adaptive radiations. Examples Perhaps the most familiar example of an evolutionary radiation is that of placental mammals immediately after the extinction of the non-avian dinosaurs at the end of the Cretaceous, about 66 million years ago. At that time, the placental mammals were mostly small, insect-eating animals similar in size and shape to modern shrews. By the Eocene (58–37 million years ago), they had evolved into such diverse forms as bats, whales, and horses. Other familiar radiations include the Avalon Explosion, the Cambrian Explosion, the Great Ordovician Biodiversification Event, the Carboniferous-Earliest Perm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DST Group
Daylight saving time (DST), also referred to as daylight savings time or simply daylight time (United States, Canada, and Australia), and summer time (United Kingdom, European Union, and others), is the practice of advancing clocks (typically by one hour) during warmer months so that darkness falls at a later clock time. The typical implementation of DST is to set clocks forward by one hour in the spring ("spring forward"), and to set clocks back by one hour in the fall ("fall back") to return to standard time. As a result, there is one 23-hour day in early spring and one 25-hour day in the middle of autumn. The idea of aligning waking hours to daylight hours to conserve candles was first proposed in 1784 by U.S. polymath Benjamin Franklin. In a satirical letter to the editor of ''The Journal of Paris'', Franklin suggested that waking up earlier in the summer would economize on candle usage; and calculated considerable savings. In 1895, New Zealand entomologist and astronome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gracilicutes
Gracilicutes (Latin: ''gracilis'', slender, and ''cutis'', skin, referring to the cell wall) is a clade in bacterial phylogeny. Traditionally gram staining results were most commonly used as a classification tool, consequently until the advent of molecular phylogeny, the Kingdom Monera (as the domains Bacteria and Archaea were known then) was divided into four phyla, * Gracilicutes (gram-negative, it is split in many groups, but some authors still use it in a narrower sense) * Firmacutes ic(gram-positive, subsequently corrected to Firmicutes, today it excludes the Actinomycetota) * Mollicutes (gram variable, later renamed Tenericutes and now Mycoplasmatota, e.g. ''Mycoplasma'') * Mendosicutes (uneven gram stain, "methanogenic bacteria" now known as methanogens and classed as Archaea) This classification system was abandoned in favour of the three-domain system based on molecular phylogeny started by C. Woese. Using hand-drawn schematics rather than standard molecular phylogenet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroflexota
The Chloroflexota are a phylum of bacteria containing isolates with a diversity of phenotypes, including members that are aerobic thermophiles, which use oxygen and grow well in high temperatures; anoxygenic phototrophs, which use light for photosynthesis (green non-sulfur bacteria); and anaerobic halorespirers, which uses halogenated organics (such as the toxic chlorinated ethenes and polychlorinated biphenyls) as electron acceptors. The members of the phylum ''Chloroflexota'' are monoderms (that is, have one cell membrane with no outer membrane), but they stain mostly gram-negative. Many well-studied phyla of bacteria are diderms and stain gram-negative, whereas well-known monoderms that stain Gram-positive include ''Firmicutes'' (or ''Bacillota'') ( low G+C gram-positives), ''Actinomycetota'' (high-G+C gram-positives) and ''Deinococcota'' (gram-positive diderms with thick peptidoglycan). History The taxon name was created in the 2001 edition of Volume 1 of Bergey's Manual of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terrabacteria
Terrabacteria is a taxon containing approximately two-thirds of prokaryote species, including those in the gram positive phyla (Actinomycetota and Bacillota) as well as the phyla "Cyanobacteria", Chloroflexota, and Deinococcota. It derives its name (''terra'' = "land") from the evolutionary pressures of life on land. Terrabacteria possess important adaptations such as resistance to environmental hazards (e.g., desiccation, ultraviolet radiation, and high salinity) and oxygenic photosynthesis. Also, the unique properties of the cell wall in gram-positive taxa, which likely evolved in response to terrestrial conditions, have contributed toward pathogenicity in many species. These results now leave open the possibility that terrestrial adaptations may have played a larger role in prokaryote evolution than currently understood. Terrabacteria was proposed in 2004 for Actinomycetota, "Cyanobacteria", and Deinococcota and was expanded later to include Bacillota and Chloroflexota. Othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gracilibacteria
Gracilibacteria is a bacterial candidate phylum formerly known as GN02, BD1-5, or SN-2. It is part of the Candidate Phyla Radiation and the Patescibacteria group. The first representative of the Gracilibacteria phylum was reported in 1999 after being recovered from a deep-sea sediment sample. The representative 16S rRNA sequence was referred to as "BD1-5" (sample BD1, sequence 5) and while it was noted that it displayed low sequence identity to any known 16S rRNA gene, it was not proposed as a new phylum at this time. In 2006, representatives of Gracilibacteria were recovered from a hypersaline microbial mat from Guerrero Negro, Baja California Sur, Mexico and proposed as a new phylum "GN02". The BD1-5/GN02 phylum was renamed "Gracilibacteria" in 2013. The first Gracilibacteria genome was recovered from an acetate-amended aquifer (Rifle, CO, USA) using culture-independent, genome-resolved metagenomic techniques in 2012. Genomic analyses suggest that members of the Gracilibacteri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saccharibacteria
Saccharibacteria, formerly known as ''TM7'', is a major bacterial lineage. It was discovered through 16S rRNA sequencing . TM7x from the human oral cavity was cultivated and revealed that TM7x is an extremely small coccus (200-300 nm) and has a distinctive lifestyle not previously observed in human-associated microbes. It is an obligate epibiont of various hosts, including ''Actinomyces odontolyticus'' strain (XH001) yet also has a parasitic phase thereby killing its host. The full genome sequence revealed a highly reduced genome (705kB) and a complete lack of amino acid biosynthetic capacity. An axenic culture of TM7 from the oral cavity was reported in 2014 but no sequence or culture was made available. Along with Candidate Phylum TM6, it was named after sequences obtained in 1994 in an environmental study of a soil sample of peat bog in Germany where 262 PCR amplified 16S rDNA fragments were cloned into a plasmid vector, named TM clones for ' ( lit. peat, middle lay ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
