519,064 articles
Arch-gravity dam
An arch-gravity dam is a curved concrete dam that resists water partly by arch action into the valley walls and partly by its own weight.
Archaea
Archaea, once called archaebacteria, are single-celled microorganisms that make up one of the three domains of life, distinct from bacteria and more closely related to eukaryotes.
Archaea Energy
Archaea Energy is a Houston-based American renewable natural gas producer founded in 2018, which turns landfill biogas into pipeline-quality fuel and was acquired by bp in 2022.
Archaea in iron and manganese cycling
Archaea in iron and manganese cycling covers dissimilatory iron and manganese transformations by archaea, from Ferroglobus placidus to manganese-reducing Methanoperedens, in vents, sediments, and acid mine drainage.
Archaea in mercury, uranium and trace metal transformations
Archaea transform mercury, arsenic, and trace metals through methylation, reduction, oxidation, and volatilization; methanogens methylate mercury via hgcAB genes, while recent studies attribute uranium reduction to bacteria rather than archaea.
Archaea of the deep subsurface
Archaea of the deep subsurface are archaeal microorganisms living in deep marine sediments, crustal fluids, and basement rock, where no light and little organic carbon reach.
Archaeal arsenic metabolism and resistance
Archaeal arsenic metabolism and resistance is the set of pathways archaea use to transform and tolerate arsenic, including ArsC reduction, Acr3 and ArsB efflux, and ArsM methylation.
Archaeal biomining and bioleaching
Archaeal biomining and bioleaching dissolve metals from sulfide ores and concentrates using extremely thermoacidophilic archaea like Sulfolobus and Acidianus at 60–80 °C, outperforming bacteria on chalcopyrite copper.
Archaeal bioremediation
Archaeal bioremediation is the use of archaea to degrade or immobilize pollutants like hydrocarbons, heavy metals, and radionuclides, exploiting their tolerance of extreme, salty, or acidic conditions.
Archaeal initiation factors
Archaeal initiation factors are the proteins that assemble a translation-competent ribosome on messenger RNA at the start of protein synthesis in archaea, including aIF1, aIF1A, aIF2, and aIF5B.
Archaeal nitrogen transformations beyond nitrification
Archaeal nitrogen transformations beyond nitrification are archaeal conversions of nitrate, nitrite, nitric oxide, nitrous oxide, and atmospheric nitrogen, including denitrification, DNRA, and nitrogen fixation in extreme habitats.
Archaeal Nre, N-terminal
Archaeal Nre, N-terminal (Nre_N, Pfam PF04894, formerly DUF650) is the N-terminal domain of the ~400-residue NreA/NreB DNA repair proteins unique to archaea, often carrying a C4 zinc-finger or [4Fe-4S] metal-binding motif of unknown function.
Archaeal rhodopsin photochemistry and photocycle
Archaeal rhodopsin photochemistry and photocycle cover how light isomerizes retinal bound to a Schiff base, driving ion pumping through intermediates J through O in bacteriorhodopsin and related pigments.
Archaeal RNA polymerase
Archaeal RNA polymerase (RNAP) is the single enzyme that transcribes all genes in archaea, with 12 or 13 subunits and a structure closely mirroring eukaryotic RNA polymerase II.
Archaeal sulfur oxidation and disproportionation
Archaeal sulfur oxidation and disproportionation: thermoacidophilic Sulfolobales oxidize elemental sulfur via sulfur oxygenase reductase (SOR), an O2-dependent disproportionation to sulfide, sulfite, and thiosulfate, distinct from bacterial sulfur dioxygenase pathways.
Archaeal sulfur reduction and sulfur respiration
Archaeal sulfur reduction and sulfur respiration: anaerobic archaeal conversion of elemental sulfur to H2S via H2- or organic-donor respiration (SR/PSR plus NiFe hydrogenase), fermentation (NSR-MBX), or assimilatory reduction, using persulfide substrates.
Archaeal symbioses
Archaeal symbioses are documented partnerships in which archaea live in sustained association with host organisms or other microbes, including gut methanogens, ANME–bacteria methane-oxidizing consortia, and archaea–archaea partnerships.
Archaeal taxa described in the 2000s
Archaeal taxa described in the 2000s is a list of archaea named from 2000 to 2009, including Nanoarchaeum equitans in 2002 and the phylum Thaumarchaeota, proposed in 2008.
Archaeal taxonomy
Archaeal taxonomy is the formal classification and naming of Archaea, covering the competing ICNP and SeqCode codes, GTDB's genome-based alternative, and the disputes over phylum and kingdom names.
Archaeal taxonomy in the 1990s
Archaeal taxonomy in the 1990s covers the naming of the domain Archaea by Woese, Kandler, and Wheelis in 1990 and the decade's new archaeal genera.
Archaeal transcription
Archaeal transcription: gene expression in Archaea via a single 11–13 subunit RNAP homologous to eukaryotic Pol II, with TBP/TFB/TFE initiation, Spt4/5 and TFS elongation, oligo(dT) intrinsic and FttA/Eta factor-dependent termination.
Archaeal transcription factor B
Archaeal transcription factor B (TFB), homolog of eukaryotic TFIIB and bacterial sigma factors, binds the BRE upstream of the TATA box with TBP and recruits archaeal RNA polymerase; many archaea encode multiple TFB isoforms.
Archaeal virus
Archaeal virus: viruses infecting Archaea, also called archaeal phage equivalents; dsDNA genomes, unique lemon, bottle, and droplet shapes; 163 species in 62 families per ICTV 2025.
Archaeoacoustics
Archaeoacoustics, also known as acoustic archaeology, is a multidisciplinary subfield of archaeology that studies the sounds and music of the past, from ancient instruments to the acoustics of caves, theaters, and monuments like Stonehenge.
Archaeoastronomy
Archaeoastronomy, also called cultural astronomy or astro-archaeology, is the interdisciplinary study of how ancient and prehistoric societies observed and used the sky, combining archaeology, astronomy, statistics, and ethnography; known for Stonehenge debates, Thom's megalithic yard, and verified sites like Chankillo.
Archaeocyatha
Archaeocyatha, archaeocyaths, ancient cups: extinct early Cambrian calcareous sponges (class within Porifera, near Demospongiae) with double-walled porous conical cups; the first skeletal reef builders, dominant in earliest Phanerozoic reefs before decline around 510 Ma.
Archaeocyathus
Archaeocyathus, an extinct Cambrian calcareous sponge genus (Billings 1861, family Archaeocyathidae, phylum Porifera) from Labrador; type genus of the reef-building Archaeocyatha, the first metazoan reef builders, known from North America, Europe, Asia, and Antarctic-Australia.
Archaeoglobales
Archaeoglobales, an order of hyperthermophilic sulfate-reducing archaea in class Archaeoglobi (GTDB: Halobacteriota), type genus Archaeoglobus; only archaeal sulfate reducers, found in hydrothermal vents and oil reservoirs, causing reservoir souring.
Archaeoglobi
Archaeoglobi is a class of hyperthermophilic, strictly anaerobic archaea, traditionally defined by dissimilatory sulfate reduction to hydrogen sulfide, first described in 1987 with an optimum growth temperature of 85 °C.
Archaeoglobus
Archaeoglobus, hyperthermophilic sulfate-reducing archaeal genus (type species A. fulgidus) from hydrothermal vents and oil reservoirs, growing at 50-90 degrees C; first sulfur-metabolizing archaeon genome-sequenced, likely polyphyletic.