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Akamé, Joseph Martial, Joseph Mvondo Ondoa, William Assatse Teikeu, Sébastien Owona, Jean Bosco Olinga, Eric José Messi Ottou, and Sylvestre Ntomba. "Apport des images Landsat-7 ETM+ à l'étude structurale du socle archéen de Sangmelima (sud Cameroun)." Revue Française de Photogrammétrie et de Télédétection, no. 206 (June 5, 2014): 15–27. http://dx.doi.org/10.52638/rfpt.2014.119.
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La région de Sangmélima est une portion du Complexe du Ntem, la terminaison septentrionale du craton du Congo d'âge archéen. Elle est située entre 2 °45' et 3 °02' N et 11 °55' et 12 °15' E. L'étude morphotectonique réalisée dans cette zone est fondée sur les techniques de traitement des images ETM+ de landsat-7 et les méthodes classiques de prospection géologique croisées à travers un système d'information géographique (SIG). L'objectif est d'évaluer l'apport de ces images dans la cartographie structurale. Les résultats obtenus mettent en évidence une déformation polyphasée D1 -D4 où D1 est soulignée par une foliation S1 globalement orientée E-W à NW-SE dans l'encaissant. D2 est représenté par les foliations S1 /2 transposées dans l'encaissant et foliation S2 dans les plutonites. L'ensemble est reprist par un épisode décrochant et transpressif conjugué D3 caractérisé par un cisaillement N-S à NE-SW. A cette D3 fait suite un épisode de déformation cassante D4 , induite par une double compression conjuguée NNW-SSE et NNE-SSW. L'extension de la télédétection à l'ensemble du domaine archéen du sud Cameroun dont l'apport s'est avéré conséquent dans la région de Sangmélima, devrait améliorer la cartographie géologique de cette région.
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Auvray, B., J. P. Burg, Ch Caruba, R. Dars, and K. Lo. "L'Amsaga (Mauritanie), fragment Archéen du Craton Ouest-Africain: observations et hypothèses nouvelles." Journal of African Earth Sciences (and the Middle East) 14, no. 2 (February 1992): 183–90. http://dx.doi.org/10.1016/0899-5362(92)90095-t.
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Edou-Minko, A., G. Grandin, and C. Campiglio. "Pétrologie et géomorphologie dans la région de Kango, Gabon: un grand dyke ultramafique-mafique archéen." Journal of African Earth Sciences 32, no. 4 (May 2001): 899–918. http://dx.doi.org/10.1016/s0899-5362(02)00062-3.
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Hébert, Réjean, Michel Rocheleau, Christine Giguère, Benoît Perrier, and Roch Gaudreau. "Pétrologie et gîtologie d'un filon-couche différencié et minéralisé archéen : le gisement aurifère Sigma-2, canton de Louvicourt, Québec." Canadian Journal of Earth Sciences 28, no. 11 (November 1, 1991): 1731–43. http://dx.doi.org/10.1139/e91-155.
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The Archean Sigma-2 orebody is hosted in the felsic granophyric zone of the differentiated Vicour sill. The sill contains anomalous gold valves and is intrusive into the uppermost part of the Val-d'Or Formation. A geochemical study shows that the Vicour sill has evolved from a ferriferous tholeiitic melt and is comagmatic with the Héva Formation to the south. The competent granophyric zone has been affected by several ductile–brittle deformation events. Three systems of faults and fractures are recognized. Each of these systems is composed of two to three subsystems. The main fault system is oriented east–west with subvertical dip and has a dextral component of movement. Two east–west oriented fault subsystems, moderately dipping (45°) towards north and south, are associated with this feature. The second major structural feature consists of northeast and north-northwest conjugate fractures superimposed on structures of the first tectonic event. The shear movement is sinistral for the northeast fractures and dextral for the north-northwest fractures. The third structural feature is the most interesting with respect to gold mineralization. It consists of east–west-trending, moderately dipping fractures that could be genetically linked with the first structural feature and resulted from a northwest–southeast compression. These fractures increased the tectonic permeability of the granophyre, which allowed Cl- and Na-rich and Ca- and CO2-poor hydrothermal fluids to circulate through the rock and produced subhorizontal mineralized quartz lenses. The lenses are composed of quartz–tourmaline ± carbonate and of pyrite–pyrrhotite ± chalcopyrite. Arsenopyrite is observed in the bleached wall rock surrounding the lenses as well as in east–west faults and northeast and north-northwest conjugate fractures. Bleaching is the result of metasomatic sericitization, albitization, silicification, and low carbonatization of the wall rock and decreases away from the mineralized lenses. Gold is associated with pyrite and arsenopyrite and occurs as inclusions and veinlets crosscutting sulfide grains. It was deposited at a late stage along with quartz and, locally, chalcopyrite. Metasomatism was responsible for the formation of arsenopyrite, coarse-grained pyrite, pyrrhotite, and chalcopyrite while ilmenite recrystallized in the veins. Fractures within arsenopyrite and pyrite are filled with late deposits of pyrrhotite and chalcopyrite. The tholeiitic composition and anomalous gold values of the mafic section of the sill could be additional valuable guidelines in the exploration for similar orebodies.
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Moyen, Jean-François, Hervé Martin, and Mudlappa Jayananda. "Origine du granite fini-Archéen de Closepet (Inde du Sud): apports de la modélisation géochimique du comportement des éléments en trace." Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science 325, no. 9 (November 1997): 659–64. http://dx.doi.org/10.1016/s1251-8050(97)89107-0.
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Corrigan, David, Natasha Wodicka, Christopher McFarlane, Isabelle Lafrance, Deanne Van Rooyen, Daniel Bandyayera, and Carl Bilodeau. "Lithotectonic Framework of the Core Zone, Southeastern Churchill Province, Canada." Geoscience Canada 45, no. 1 (April 20, 2018): 1–24. http://dx.doi.org/10.12789/geocanj.2018.45.128.
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The Core Zone, a broad region located between the Superior and North Atlantic cratons and predominantly underlain by Archean gneiss and granitoid rocks, remained until recently one of the less well known parts of the Canadian Shield. Previously thought to form part of the Archean Rae Craton, and later referred to as the Southeastern Churchill Province, it has been regarded as an ancient continental block trapped between the Paleoproterozoic Torngat and New Quebec orogens, with its relationships to the adjacent Superior and North Atlantic cratons remaining unresolved. The geochronological data presented herein suggest that the Archean evolution of the Core Zone was distinct from that in both the Superior and North Atlantic (Nain) cratons. Moreover, the Core Zone itself consists of at least three distinct lithotectonic entities with different evolutions, referred to herein as the George River, Mistinibi-Raude and Falcoz River blocks, that are separated by steeply-dipping, crustal-scale shear zones interpreted as paleosutures. Specifically, the George River Block consists of ca. 2.70 Ga supracrustal rocks and associated ca. 2.70–2.57 Ga intrusions. The Mistinibi-Raude Block consists of remnants of a ca. 2.37 Ga volcanic arc intruded by a ca. 2.32 Ga arc plutonic suite (Pallatin) and penecontemporaneous alkali plutons (Pelland and Nekuashu suites). It also hosts a coarse clastic cover sequence (the Hutte Sauvage Group) which contains detrital zircons provided from locally-derived, ca. 2.57–2.50 Ga, 2.37–2.32 Ga, and 2.10–2.08 Ga sources, with the youngest concordant grain dated at 1987 ± 7 Ma. The Falcoz River Block consists of ca. 2.89–2.80 Ga orthogneiss intruded by ca. 2.74–2.70 granite, tonalite, and granodiorite. At the western margin of the Core Zone, the George River Block and Kuujjuaq Domain may have been proximal by ca. 1.84 Ga as both appear to have been sutured by the 1.84–1.82 Ga De Pas Batholith, whereas at its eastern margin, the determination of metamorphic ages of ca. 1.85 to 1.80 Ga in the Falcoz River Block suggests protracted interaction with the adjacent Lac Lomier Complex during their amalgamation and suturing, but with a younger, ‘New Quebec’ overprint as well. The three crustal blocks forming the Core Zone add to a growing list of ‘exotic’ Archean to earliest Paleoproterozoic microcontinents and crustal slices that extend around the Superior Craton from the Grenville Front through Hudson Strait, across Hudson Bay and into Manitoba and Saskatchewan, in what was the Manikewan Ocean realm, which closed between ca. 1.83–1.80 Ga during the formation of supercontinent Nuna.RÉSUMÉLa Zone noyau, une vaste région située entre les cratons du Supérieur et de l’Atlantique Nord et reposant principalement sur des gneiss archéens et des roches granitiques, est demeurée jusqu’à récemment l’une des parties les moins bien connues du Bouclier canadien. Considérée auparavant comme faisant partie du craton archéen de Rae, puis comme la portion sud-est de la Province de Churchill, on l’a perçue comme un ancien bloc continental piégé entre les orogènes paléoprotérozoïques des Torngat et du Nouveau-Québec, ses relations avec les cratons supérieurs adjacents et de l’Atlantique Nord demeurant nébuleuses. Les données géochronologiques présentées ici permettent de penser que l’évolution archéenne de la Zone noyau a été différente de celle des cratons du Supérieur et de l’Atlantique Nord (Nain). De plus, la Zone noyau elle-même se compose d’au moins trois entités lithotectoniques distinctes avec des évolutions différentes, appelées ici les blocs de la rivière George, de Mistinibi-Raude et de la rivière Falcoz, lesquels sont séparées par des zones de cisaillement crustales à forte inclinaison, conçues comme des paléosutures. Plus précisément, le bloc de la rivière George est constitué de roches supracrustales d'env. 2,70 Ga, et d’intrusions connexes d'env. 2,70–2,57 Ga. Le bloc Mistinibi-Raude est constitué de vestiges d’un arc volcanique d'env. 2,37 Ga, recoupé par une suite plutonique d’arc d'env. 2,32 Ga (Pallatin) et de plutons alcalins péné-contemporains (suites Pelland et Nekuashu). Il contient également une séquence de couverture clastique grossière (le groupe Hutte Sauvage) renfermant des zircons détritiques de sources locales, âgés d'env. 2,57–2,50 Ga, 2,37–2,32 Ga et 2,10–2,08 Ga, le grain concordant le plus jeune étant âgé de 1987 ± 7 Ma. Le bloc de la rivière Falcoz est formé d’un orthogneiss âgé d'env. 2,89–2,80 Ga, recoupé par des intrusions de granite, tonalite et granodiorite âgées d'env. 2,74–2,70 Ga. À la marge ouest de la Zone noyau, le bloc de la rivière George et du domaine de Kuujjuaq peuvent avoir été proximaux il y a 1,84 Ga env., car les deux semblent avoir été suturés par le batholithe De Pas il y a environ 1,84–1,82 Ga, alors qu’à sa marge est, la détermination des datations métamorphiques de 1,85 à 1,80 Ga dans le bloc de la rivière Falcoz suggère une interaction prolongée avec le complexe adjacent du lac Lomier durant leur amalgamation et leur suture, mais affecté aussi d’une surimpression « Nouveau Québec » plus jeune. Les trois blocs crustaux formant la Zone noyau s’ajoutent à une liste croissante de micro-continents et d’écailles crustales « exotiques » archéennes à paléoprotérozoïques très précoces qui s’étalent autour du craton Supérieur depuis le front de Grenville jusqu’au Manitoba, à travers le détroit d’Hudson, la baie d’Hudson jusque dans le Manitoba et la Saskatchewan, là où s’étendait l’océan Manikewan, lequel s’est refermé il y a environ 1,83–1,80 Ga, pendant la formation du supercontinent Nuna.
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Vishiti, Akumbom, Dieudonne Charles Isidore Ilouga, Ndzegha Collins Bomyoymoah, and Cheo Emmanuel Suh. "Petrology of banded iron formation-related country rocks at the northern limit of the Mbalam iron ore district, southeastern Cameroon." Journal of the Cameroon Academy of Sciences 18, no. 2 (October 24, 2022): 447–72. http://dx.doi.org/10.4314/jcas.v18i2.5.
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Banded iron formation (BIF)-related country rocks at the northern limit of the Mbalam iron ore district constitute part of the Archean to Proterozoic greenstone belt of the Congo Craton (CC). In this study the petrology of BIFs and amphibolites from the lower part of the Njweng ridge is presented in a bid to decipher the source of the sediments and their inherent iron enrichment. The BIFs vary from oxide to silicate facies categories, composed mainly of magnetite bands alternating with quartz bands and their mineralogy is dominated by magnetite, hematite and quartz. The amphibolites contain quartz, magnetite, amphibole, biotite, garnet with a distinct schistocity. The Fe2O3 and SiO2 content of the BIFs reach highs of 54.55 wt% and 57.83 wt%, respectively. The average Fe2O3 content of 46.7 wt% coupled with SiO2 and Al2O3 as deleterious elements indicate a relatively low-grade iron ore. Gold content reaches a maximum of 1.1 ppb. Low Al2O3, TiO2 and High Field Strength Elements (HFSE) indicate BIF derivation from detritus-free chemical sediments. Their Fe/Ti, Fe/Al and Si/Al ratios are typical of marine BIF systems with hydrothermal overprint. On Post Archaean Australian Shale (PAAS)-normalized Rare Earth Elements-Yttrium (REE-Y) patterns the BIFs present a slightly negative Ce anomaly and positive Eu and Y anomalies; characteristics typical of modern seawater. The amphibolites are enriched in Light Rare Earth Elements (LREE) relative to Heavy Rare Earth Elements (HREE) and show peaks of Y, Nb, La Ta and their Au content attains a maximum of 1.7 ppm. Gold contents in the BIFs and amphibolites indicate the BIF-related country rocks as a potential primary source of the alluvial gold mined in the Mbalam district.
Les gisements de Fer rubanés (BIFs) localisés à la limite Nord du district ferrifere de Mbalam, sont partiellement représentatives des ceintures de roches vertes Archéennes à Protérozoïques dans le Craton du Congo (CC). Dans cette étude, la pétrologie des BIFs et amphibolites de la partie inferieure de la crête de Njweng est présentée afin de déceler la source des sédiments ainsi que leur enrichissement en Fer. Différentes catégories de BIFs variant des facies à oxydes aux silicates, sont composées principalement de bandes à magnétite avec alternances de bandes quartzeux. Leur minéralogie est dominée par la magnétite, l’hématite et le quartz. Les amphibolites contiennent du quartz, magnétite, l’amphibole, biotite, et grenat avec une schistosité distincte. La teneur en Fe2O3 et SiO2 des BIFs atteint un maximum en poids de 54,55 % et 57,83 % respectivement. La teneur moyenne en Fe2O3 de 46,7 % en poids, associée au SiO2 et Al2O3 comme éléments délétères, indique un minerai de fer à teneur relativement faible. Les teneurs en Or atteignent un maximum de 1,1 ppb. Les faibles teneurs en Al2O3, TiO2 et élément de champ électrostatique élevé (HFSE) indiquent que les BIFs dérivent d’un environnement sédimentaire chimique d’origine non détritique. Leur rapports Fe/Ti, Fe/Al et Si/Al sont typiques des systèmes BIFs marin avec une signature hydrothermale. Sur les modèles tarres rares-yttrium normalisés par schiste australien post- archéen (PAAS), les BIFs révèlent une légère anomalie négative de Ce couplée à une anomalie positive de Eu et Y, caractéristique d’un environnement marin récent. Les amphibolites sont enrichies en tarres rares légères par rapport aux tarres rares lourdes et montrent des pics de Y, Nb, La et Ta, Leurs teneurs en Au atteignent un maximum de 1,7 ppm. Les teneurs en Or dans les BIFs et les amphibolites indiquent que les formations de fer rubanées (BIFs) en place dans le district de Mbalam sont une source potentielle d’or.
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Billa, Mario, Jean-Louis Feybesse, Georges Bronner, Catherine Lerouge, Jean-Pierre Milési, Sory Traoré, and Sory Diaby. "Les formations à quartzites rubanés ferrugineux des Monts Nimba et du Simandou: des unités empilées tectoniquement, sur un « soubassementplutonique Archéen (craton de Kénéma-Man), lors de l'orogène Éburnéen." Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science 329, no. 4 (August 1999): 287–94. http://dx.doi.org/10.1016/s1251-8050(99)80248-1.
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Woźniacka, Renata, Łukasz Oleksy, Agnieszka Jankowicz-Szymańska, Anna Mika, Renata Kielnar, and Artur Stolarczyk. "The Association between Symmetrical or Asymmetrical High-Arched Feet and Muscle Fatigue in Young Women." Symmetry 14, no. 1 (January 1, 2022): 52. http://dx.doi.org/10.3390/sym14010052.
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The foot arches are responsible for proper foot loading, optimal force distribution, and transmission throughout the soft tissues. Since the foot arch is an elastic structure, able to adapt to forces transmitted by the foot, it was reported that low arch is related to excessive foot pronation, while high arched foot is more rigid and inflexible. Therefore, it is also probable, that foot arch alterations may change the force transmission via myofascial chains. The objective of this study was to evaluate the effect of symmetrical and asymmetrical excessive feet arching on muscle fatigue in the distal body parts such as the lower limbs, trunk, and head. Seventy-seven women (25.15 ± 5.97 years old, 62 ± 10 kg, 167 ± 4 cm) were assigned to three groups according to the foot arch index (Group 1—both feet with normal arch, Group 2—one foot with normal arch and the other high-arched, Group 3—both feet with high-arch). The bioelectrical activity of the right and left hamstrings muscles, erector spine, masseter, and temporalis muscle was recorded by sEMG during the isometric contraction lasting for 60 s. The stable intensity of the muscle isometric contraction was kept for all the time during the measurement. Mean frequency difference (%), slope (Hz), and intercept (Hz) values were calculated for muscle fatigue evaluation. No differences were observed in fatigue variables for all evaluated muscles between the right and left side in women with symmetrical foot arches, but in the group with asymmetric foot arches, the higher muscle fatigue on the normal-arched side compared to the high-arched side was noted. Significantly greater values of the semitendinosus—semimembranosus muscle frequency difference was observed on the normal-arched side compared to the high-arched side (p = 0.04; ES = 0.52; −29.5 ± 9.1% vs. −24.9 ± 8.4%). In the group with asymmetric foot arches, a significantly higher value of lumbar erector spinae muscle frequency slope (p = 0.01; ES = 1.32; −0.20 ± 0.04 Hz vs. −0.14 ± 0.05 Hz) and frequency difference (p = 0.04; ES = 0.92; −7.8 ± 3.1% vs. −4.8 ± 3.4%) were observed on the high-arched foot side compared to the side with normal foot arching. The thoracic erector spine muscle frequency slope was significantly larger in women with asymmetrical arches than in those with both feet high-arched (right side: p = 0.01; ES = 1.25; −0.20 ± 0.08 Hz vs. −0.10 ± 0.08 Hz); (left side: p = 0.005; ES = 1,17; −0.19 ± 0.04 Hz vs. −0.13 ± 0.06 Hz) and compared to those with normal feet arches (right side: p = 0.02; ES = 0.58; −0.20 ± 0.08 Hz vs. −0.15 ± 0.09 Hz); (left side: p = 0.005; ES = 0.87; −0.19 ± 0.04 Hz vs. −0.14 ± 0.07 Hz). In the group with asymmetric foot arches, the frequency difference was significantly higher compared to those with both feet high-arched (right side: p = 0.01; ES = 0.87; −15.4 ± 6.8% vs. 10.4 ± 4.3%); (left side: p = 0.01; ES = 0.96; 16.1 ± 6.5% vs. 11.1 ± 3.4%). In the group with asymmetric foot arches, a significantly higher value of the masseter muscle frequency difference was observed on the high-arched side compared to the normal-arched side (p = 0.01; ES = 0.95; 6.91 ± 4.1% vs. 3.62 ± 2.8%). A little increase in the longitudinal arch of the foot, even though such is often not considered as pathological, may cause visible changes in muscle function, demonstrated as elevated signs of muscles fatigue. This study suggests that the consequences of foot high-arching may be present in distal body parts. Any alterations of the foot arch should be considered as a potential foot defect, and due to preventing muscle overloading, some corrective exercises or/and corrective insoles for shoes should be used. It can potentially reduce both foot overload and distant structures overload, which may diminish musculoskeletal system pain and dysfunctions.
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Harish, Ajith. "What is an archaeon and are the Archaea really unique?" PeerJ 6 (October 18, 2018): e5770. http://dx.doi.org/10.7717/peerj.5770.
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The recognition of the group Archaea as a major branch of the tree of life (ToL) prompted a new view of the evolution of biodiversity. The genomic representation of archaeal biodiversity has since significantly increased. In addition, advances in phylogenetic modeling of multi-locus datasets have resolved many recalcitrant branches of the ToL. Despite the technical advances and an expanded taxonomic representation, two important aspects of the origins and evolution of the Archaea remain controversial, even as we celebrate the 40th anniversary of the monumental discovery. These issues concern (i) the uniqueness (monophyly) of the Archaea, and (ii) the evolutionary relationships of the Archaea to the Bacteria and the Eukarya; both of these are relevant to the deep structure of the ToL. To explore the causes for this persistent ambiguity, I examine multiple datasets and different phylogenetic approaches that support contradicting conclusions. I find that the uncertainty is primarily due to a scarcity of information in standard datasets—universal core-genes datasets—to reliably resolve the conflicts. These conflicts can be resolved efficiently by comparing patterns of variation in the distribution of functional genomic signatures, which are less diffused unlike patterns of primary sequence variation. Relatively lower heterogeneity in distribution patterns minimizes uncertainties and supports statistically robust phylogenetic inferences, especially of the earliest divergences of life. This case study further highlights the limitations of primary sequence data in resolving difficult phylogenetic problems, and raises questions about evolutionary inferences drawn from the analyses of sequence alignments of a small set of core genes. In particular, the findings of this study corroborate the growing consensus that reversible substitution mutations may not be optimal phylogenetic markers for resolving early divergences in the ToL, nor for determining the polarity of evolutionary transitions across the ToL.
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Liew, Li Phing, and Stephen D. Bell. "The interplay of DNA binding, ATP hydrolysis and helicase activities of the archaeal MCM helicase." Biochemical Journal 436, no. 2 (May 13, 2011): 409–14. http://dx.doi.org/10.1042/bj20110084.
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The MCM (minichromosome maintenance) proteins of archaea are widely believed to be the replicative DNA helicase of these organisms. Most archaea possess a single MCM orthologue that forms homo-multimeric assemblies with a single hexamer believed to be the active form. In the present study we characterize the roles of highly conserved residues in the ATPase domain of the MCM of the hyperthermophilic archaeon Sulfolobus solfataricus. Our results identify a potential conduit for communicating DNA-binding information to the ATPase active site.
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Nickel, Astrid I., Nadine B. Wäber, Markus Gößringer, Marcus Lechner, Uwe Linne, Ursula Toth, Walter Rossmanith, and Roland K. Hartmann. "Minimal and RNA-free RNase P in Aquifex aeolicus." Proceedings of the National Academy of Sciences 114, no. 42 (October 3, 2017): 11121–26. http://dx.doi.org/10.1073/pnas.1707862114.
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RNase P is an essential tRNA-processing enzyme in all domains of life. We identified an unknown type of protein-only RNase P in the hyperthermophilic bacterium Aquifex aeolicus: Without an RNA subunit and the smallest of its kind, the 23-kDa polypeptide comprises a metallonuclease domain only. The protein has RNase P activity in vitro and rescued the growth of Escherichia coli and Saccharomyces cerevisiae strains with inactivations of their more complex and larger endogenous ribonucleoprotein RNase P. Homologs of Aquifex RNase P (HARP) were identified in many Archaea and some Bacteria, of which all Archaea and most Bacteria also encode an RNA-based RNase P; activity of both RNase P forms from the same bacterium or archaeon could be verified in two selected cases. Bioinformatic analyses suggest that A. aeolicus and related Aquificaceae likely acquired HARP by horizontal gene transfer from an archaeon.
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Brázda, Václav, Yu Luo, Martin Bartas, Patrik Kaura, Otilia Porubiaková, Jiří Šťastný, Petr Pečinka, et al. "G-Quadruplexes in the Archaea Domain." Biomolecules 10, no. 9 (September 21, 2020): 1349. http://dx.doi.org/10.3390/biom10091349.
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The importance of unusual DNA structures in the regulation of basic cellular processes is an emerging field of research. Amongst local non-B DNA structures, G-quadruplexes (G4s) have gained in popularity during the last decade, and their presence and functional relevance at the DNA and RNA level has been demonstrated in a number of viral, bacterial, and eukaryotic genomes, including humans. Here, we performed the first systematic search of G4-forming sequences in all archaeal genomes available in the NCBI database. In this article, we investigate the presence and locations of G-quadruplex forming sequences using the G4Hunter algorithm. G-quadruplex-prone sequences were identified in all archaeal species, with highly significant differences in frequency, from 0.037 to 15.31 potential quadruplex sequences per kb. While G4 forming sequences were extremely abundant in Hadesarchaea archeon (strikingly, more than 50% of the Hadesarchaea archaeon isolate WYZ-LMO6 genome is a potential part of a G4-motif), they were very rare in the Parvarchaeota phylum. The presence of G-quadruplex forming sequences does not follow a random distribution with an over-representation in non-coding RNA, suggesting possible roles for ncRNA regulation. These data illustrate the unique and non-random localization of G-quadruplexes in Archaea.
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Woodson, J. D., R. F. Peck, M. P. Krebs, and J. C. Escalante-Semerena. "The cobY Gene of the Archaeon Halobacterium sp. Strain NRC-1 Is Required for De Novo Cobamide Synthesis." Journal of Bacteriology 185, no. 1 (January 1, 2003): 311–16. http://dx.doi.org/10.1128/jb.185.1.311-316.2003.
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ABSTRACT Genetic and nutritional analyses of mutants of the extremely halophilic archaeon Halobacterium sp. strain NRC-1 showed that open reading frame (ORF) Vng1581C encodes a protein with nucleoside triphosphate:adenosylcobinamide-phosphate nucleotidyltransferase enzyme activity. This activity was previously associated with the cobY gene of the methanogenic archaeon Methanobacterium thermoautotrophicum strain ΔH, but no evidence was obtained to demonstrate the direct involvement of this protein in cobamide biosynthesis in archaea. Computer analysis of the Halobacterium sp. strain NRC-1 ORF Vng1581C gene and the cobY gene of M. thermoautotrophicum strain ΔH showed the primary amino acid sequence of the proteins encoded by these two genes to be 35% identical and 48% similar. A strain of Halobacterium sp. strain NRC-1 carrying a null allele of the cobY gene was auxotrophic for cobinamide-GDP, a known intermediate of the late steps of cobamide biosynthesis. The auxotrophic requirement for cobinamide-GDP was corrected when a wild-type allele of cobY was introduced into the mutant strain, demonstrating that the lack of cobY function was solely responsible for the observed block in cobamide biosynthesis in this archaeon. The data also show that Halobacterium sp. strain NRC-1 possesses a high-affinity transport system for corrinoids and that this archaeon can synthesize cobamides de novo under aerobic growth conditions. To the best of our knowledge this is the first genetic and nutritional analysis of cobalamin biosynthetic mutants in archaea.
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Scott, Joseph W., and Madeline E. Rasche. "Purification, Overproduction, and Partial Characterization of β-RFAP Synthase, a Key Enzyme in the Methanopterin Biosynthesis Pathway†." Journal of Bacteriology 184, no. 16 (August 15, 2002): 4442–48. http://dx.doi.org/10.1128/jb.184.16.4442-4448.2002.
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ABSTRACT Methanopterin is a folate analog involved in the C1 metabolism of methanogenic archaea, sulfate-reducing archaea, and methylotrophic bacteria. Although a pathway for methanopterin biosynthesis has been described in methanogens, little is known about the enzymes and genes involved in the biosynthetic pathway. The enzyme β-ribofuranosylaminobenzene 5′-phosphate synthase (β-RFAP synthase) catalyzes the first unique step to be identified in the pathway of methanopterin biosynthesis, namely, the condensation of p-aminobenzoic acid with phosphoribosylpyrophosphate to form β-RFAP, CO2, and inorganic pyrophosphate. The enzyme catalyzing this reaction has not been purified to homogeneity, and the gene encoding β-RFAP synthase has not yet been identified. In the present work, we report on the purification to homogeneity of β-RFAP synthase. The enzyme was purified from the methane-producing archaeon Methanosarcina thermophila, and the N-terminal sequence of the protein was used to identify corresponding genes from several archaea, including the methanogen Methanococcus jannaschii and the sulfate-reducing archaeon Archaeoglobus fulgidus. The putative β-RFAP synthase gene from A. fulgidus was expressed in Escherichia coli, and the enzymatic activity of the recombinant gene product was verified. A BLAST search using the deduced amino acid sequence of the β-RFAP synthase gene identified homologs in additional archaea and in a gene cluster required for C1 metabolism by the bacterium Methylobacterium extorquens. The identification of a gene encoding a potential β-RFAP synthase in M. extorquens is the first report of a putative methanopterin biosynthetic gene found in the Bacteria and provides evidence that the pathways of methanopterin biosynthesis in Bacteria and Archaea are similar.
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Yang, Ying, Rie Yatsunami, Ai Ando, Nobuhiro Miyoko, Toshiaki Fukui, Shinichi Takaichi, and Satoshi Nakamura. "Complete Biosynthetic Pathway of the C50Carotenoid Bacterioruberin from Lycopene in the Extremely Halophilic Archaeon Haloarcula japonica." Journal of Bacteriology 197, no. 9 (February 23, 2015): 1614–23. http://dx.doi.org/10.1128/jb.02523-14.
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ABSTRACTHaloarcula japonica, an extremely halophilic archaeon that requires high concentrations of NaCl for growth, accumulates the C50carotenoid bacterioruberin (BR). By homology analysis, a gene cluster, includingc0507,c0506, andc0505, was found and predicted to be involved in the synthesis of bacterioruberin. To elucidate the function of the encoded enzymes, we constructedHa. japonicamutants of these genes and analyzed carotenoids produced by the mutants. Our research showed thatc0507,c0506, andc0505encoded a carotenoid 3,4-desaturase (CrtD), a bifunctional lycopene elongase and 1,2-hydratase (LyeJ), and a C50carotenoid 2″,3″-hydratase (CruF), respectively. The above three carotenoid biosynthetic enzymes catalyze the reactions that convert lycopene to bacterioruberin inHa. japonica. This is the first identification of functional CrtD and CruF in archaea and elucidation of the complete biosynthetic pathway of bacterioruberin from lycopene.IMPORTANCEHaloarcula japonica, an extremely halophilic archaeon, accumulates the C50carotenoid bacterioruberin (BR). In this study, we have identified three BR biosynthetic enzymes and have elucidated their functions. Among them, two enzymes were found in an archaeon for the first time. Our results revealed the biosynthetic pathway responsible for production of BR inHa. japonicaand provide a basis for investigating carotenoid biosynthetic pathways in other extremely halophilic archaea. Elucidation of the carotenoid biosynthetic pathway inHa. japonicamay also prove useful for producing the C50carotenoid BR efficiently by employing genetically modified haloarchaeal strains.
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Sandaa, Ruth-Anne, Øivind Enger, and Vigdis Torsvik. "Abundance and Diversity of Archaea in Heavy-Metal-Contaminated Soils." Applied and Environmental Microbiology 65, no. 8 (August 1, 1999): 3293–97. http://dx.doi.org/10.1128/aem.65.8.3293-3297.1999.
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ABSTRACT The impact of heavy-metal contamination on archaean communities was studied in soils amended with sewage sludge contaminated with heavy metals to varying extents. Fluorescent in situ hybridization showed a decrease in the percentage of Archaea from 1.3% ± 0.3% of 4′,6-diamidino-2-phenylindole-stained cells in untreated soil to below the detection limit in soils amended with heavy metals. A comparison of the archaean communities of the different plots by denaturing gradient gel electrophoresis revealed differences in the structure of the archaean communities in soils with increasing heavy-metal contamination. Analysis of cloned 16S ribosomal DNA showed close similarities to a unique and globally distributed lineage of the kingdom Crenarchaeota that is phylogenetically distinct from currently characterized crenarchaeotal species.
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Forterre, Patrick. "The Common Ancestor of Archaea and Eukarya Was Not an Archaeon." Archaea 2013 (2013): 1–18. http://dx.doi.org/10.1155/2013/372396.
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It is often assumed that eukarya originated from archaea. This view has been recently supported by phylogenetic analyses in which eukarya are nested within archaea. Here, I argue that these analyses are not reliable, and I critically discuss archaeal ancestor scenarios, as well as fusion scenarios for the origin of eukaryotes. Based on recognized evolutionary trends toward reduction in archaea and toward complexity in eukarya, I suggest that their last common ancestor was more complex than modern archaea but simpler than modern eukaryotes (the bug in-between scenario). I propose that the ancestors of archaea (and bacteria) escaped protoeukaryotic predators by invading high temperature biotopes, triggering their reductive evolution toward the “prokaryotic” phenotype (the thermoreduction hypothesis). Intriguingly, whereas archaea and eukarya share many basic features at the molecular level, the archaeal mobilome resembles more the bacterial than the eukaryotic one. I suggest that selection of different parts of the ancestral virosphere at the onset of the three domains played a critical role in shaping their respective biology. Eukarya probably evolved toward complexity with the help of retroviruses and large DNA viruses, whereas similar selection pressure (thermoreduction) could explain why the archaeal and bacterial mobilomes somehow resemble each other.
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Sakuraba, Haruhiko, Ryushi Kawakami, Hajime Takahashi, and Toshihisa Ohshima. "Novel Archaeal Alanine:Glyoxylate Aminotransferase from Thermococcus litoralis." Journal of Bacteriology 186, no. 16 (August 15, 2004): 5513–18. http://dx.doi.org/10.1128/jb.186.16.5513-5518.2004.
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ABSTRACT A novel alanine:glyoxylate aminotransferase was found in a hyperthermophilic archaeon, Thermococcus litoralis. The amino acid sequence of the enzyme did not show a similarity to any alanine:glyoxylate aminotransferases reported so far. Homologues of the enzyme appear to be present in almost all hyperthermophilic archaea whose whole genomes have been sequenced.
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Hemmi, Hisashi, Satoshi Yamashita, Takefumi Shimoyama, Toru Nakayama, and Tokuzo Nishino. "Cloning, Expression, and Characterization ofcis-Polyprenyl Diphosphate Synthase from the Thermoacidophilic Archaeon Sulfolobus acidocaldarius." Journal of Bacteriology 183, no. 1 (January 1, 2001): 401–4. http://dx.doi.org/10.1128/jb.183.1.401-404.2001.
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ABSTRACT cis-polyprenyl diphosphate synthases are involved in the biosynthesis of the glycosyl carrier lipid in most organisms. However, only little is known about this enzyme of archaea. In this report, we isolated the gene of cis-polyprenyl diphosphate synthase from a thermoacidophilic archaeon, Sulfolobus acidocaldarius, and characterized the recombinant enzyme.
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Imachi, Hiroyuki, Masaru K. Nobu, Nozomi Nakahara, Yuki Morono, Miyuki Ogawara, Yoshihiro Takaki, Yoshinori Takano, et al. "Isolation of an archaeon at the prokaryote–eukaryote interface." Nature 577, no. 7791 (January 15, 2020): 519–25. http://dx.doi.org/10.1038/s41586-019-1916-6.
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Abstract The origin of eukaryotes remains unclear1–4. Current data suggest that eukaryotes may have emerged from an archaeal lineage known as ‘Asgard’ archaea5,6. Despite the eukaryote-like genomic features that are found in these archaea, the evolutionary transition from archaea to eukaryotes remains unclear, owing to the lack of cultured representatives and corresponding physiological insights. Here we report the decade-long isolation of an Asgard archaeon related to Lokiarchaeota from deep marine sediment. The archaeon—‘Candidatus Prometheoarchaeum syntrophicum’ strain MK-D1—is an anaerobic, extremely slow-growing, small coccus (around 550 nm in diameter) that degrades amino acids through syntrophy. Although eukaryote-like intracellular complexes have been proposed for Asgard archaea6, the isolate has no visible organelle-like structure. Instead, Ca. P. syntrophicum is morphologically complex and has unique protrusions that are long and often branching. On the basis of the available data obtained from cultivation and genomics, and reasoned interpretations of the existing literature, we propose a hypothetical model for eukaryogenesis, termed the entangle–engulf–endogenize (also known as E3) model.
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Kuznetsov, V. G. "Geochemical environments of the Archean-Proterozoic." Доклады Академии наук 488, no. 4 (October 10, 2019): 403–7. http://dx.doi.org/10.31857/s0869-56524884403-407.
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In the Precambrian section, there is a change of Archean calcite carbonate rocks to magnesia and ferrous in the Proterozoic. This is correlated with the massive development of cyanobacteria, the absorption of which carbon dioxide and the generation of oxygen, led to a change in the acidic reduction conditions of Archaean alkaline oxidizing in the Proterozoic.
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Malki, Liron, Michaela Yanku, Ilya Borovok, Gerald Cohen, Moshe Mevarech, and Yair Aharonowitz. "Identification and Characterization of gshA, a Gene Encoding the Glutamate-Cysteine Ligase in the Halophilic Archaeon Haloferax volcanii." Journal of Bacteriology 191, no. 16 (June 12, 2009): 5196–204. http://dx.doi.org/10.1128/jb.00297-09.
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ABSTRACT Halophilic archaea were found to contain in their cytoplasm millimolar concentrations of γ-glutamylcysteine (γGC) instead of glutathione. Previous analysis of the genome sequence of the archaeon Halobacterium sp. strain NRC-1 has indicated the presence of a sequence homologous to sequences known to encode the glutamate-cysteine ligase GshA. We report here the identification of the gshA gene in the extremely halophilic archaeon Haloferax volcanii and show that H. volcanii gshA directs in vivo the synthesis and accumulation of γGC. We also show that the H. volcanii gene when expressed in an Escherichia coli strain lacking functional GshA is able to restore synthesis of glutathione.
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Large, Andrew T., Martin D. Goldberg, and Peter A. Lund. "Chaperones and protein folding in the archaea." Biochemical Society Transactions 37, no. 1 (January 20, 2009): 46–51. http://dx.doi.org/10.1042/bst0370046.
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A survey of archaeal genomes for the presence of homologues of bacterial and eukaryotic chaperones reveals several interesting features. All archaea contain chaperonins, also known as Hsp60s (where Hsp is heat-shock protein). These are more similar to the type II chaperonins found in the eukaryotic cytosol than to the type I chaperonins found in bacteria, mitochondria and chloroplasts, although some archaea also contain type I chaperonin homologues, presumably acquired by horizontal gene transfer. Most archaea contain several genes for these proteins. Our studies on the type II chaperonins of the genetically tractable archaeon Haloferax volcanii have shown that only one of the three genes has to be present for the organisms to grow, but that there is some evidence for functional specialization between the different chaperonin proteins. All archaea also possess genes for prefoldin proteins and for small heat-shock proteins, but they generally lack genes for Hsp90 and Hsp100 homologues. Genes for Hsp70 (DnaK) and Hsp40 (DnaJ) homologues are only found in a subset of archaea. Thus chaperone-assisted protein folding in archaea is likely to display some unique features when compared with that in eukaryotes and bacteria, and there may be important differences in the process between euryarchaea and crenarchaea.
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Moussard, Hélène, Ghislaine Henneke, David Moreira, Vincent Jouffe, Purificacion López-García, and Christian Jeanthon. "Thermophilic Lifestyle for an Uncultured Archaeon from Hydrothermal Vents: Evidence from Environmental Genomics." Applied and Environmental Microbiology 72, no. 3 (March 2006): 2268–71. http://dx.doi.org/10.1128/aem.72.3.2268-2271.2006.
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ABSTRACT We present a comparative analysis of two genome fragments isolated from a diverse and widely distributed group of uncultured euryarchaea from deep-sea hydrothermal vents. The optimal activity and thermostability of a DNA polymerase predicted in one fragment were close to that of the thermophilic archaeon Thermoplasma acidophilum, providing evidence for a thermophilic way of life of this group of uncultured archaea.
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Gudhka, Reema K., Brett A. Neilan, and Brendan P. Burns. "Adaptation, Ecology, and Evolution of the Halophilic Stromatolite ArchaeonHalococcus hamelinensisInferred through Genome Analyses." Archaea 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/241608.
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Halococcus hamelinensiswas the first archaeon isolated from stromatolites. These geomicrobial ecosystems are thought to be some of the earliest known on Earth, yet, despite their evolutionary significance, the role of Archaea in these systems is still not well understood. Detailed here is the genome sequencing and analysis of an archaeon isolated from stromatolites. The genome ofH. hamelinensisconsisted of 3,133,046 base pairs with an average G+C content of 60.08% and contained 3,150 predicted coding sequences or ORFs, 2,196 (68.67%) of which were protein-coding genes with functional assignments and 954 (29.83%) of which were of unknown function. Codon usage of theH. hamelinensisgenome was consistent with a highly acidic proteome, a major adaptive mechanism towards high salinity. Amino acid transport and metabolism, inorganic ion transport and metabolism, energy production and conversion, ribosomal structure, and unknown function COG genes were overrepresented. The genome ofH. hamelinensisalso revealed characteristics reflecting its survival in its extreme environment, including putative genes/pathways involved in osmoprotection, oxidative stress response, and UV damage repair. Finally, genome analyses indicated the presence of putative transposases as well as positive matches of genes ofH. hamelinensisagainst various genomes of Bacteria, Archaea, and viruses, suggesting the potential for horizontal gene transfer.
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Burgess, Stuart, Alex Beeston, Joshua Carr, Kallia Siempou, Maya Simmonds, and Yasmin Zanker. "A Bio-Inspired Arched Foot with Individual Toe Joints and Plantar Fascia." Biomimetics 8, no. 6 (September 26, 2023): 455. http://dx.doi.org/10.3390/biomimetics8060455.
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This paper presents the design and testing of an arched foot with several biomimetic features, including five individual MTP (toe) joints, four individual midfoot joints, and plantar fascia. The creation of a triple-arched foot represents a step further in bio-inspired design compared to other published designs. The arched structure creates flexibility that is similar to human feet with a vertical deflection of up to 12 mm. The individual toe joints enable abduction–adduction in the forefoot and therefore a natural pronation motion. Adult female bone data was obtained and converted into a CAD model to accurately identify the location of bones, joints, and arches. An analytical model is presented that gives the relationship between the vertical stiffness and horizontal stiffness of the longitudinal arches and therefore allows the optimization of stiffness elements. Experimental tests have demonstrated a vertical arch stiffness of 76 N/mm which is similar to adult human feet. The range of movement of the foot is similar to human feet with the following values: dorsi-plantarflexion (28°/37°), inversion-eversion (30°/15°), and abduction–adduction (30°/39°). Tests have also demonstrated a three-point contact with the ground that is similar to human feet.
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La Flèche, M. R., T. C. Birkett, and L. Corriveau. "Crustal development at the pre-Grenvillian Laurentian margin: a record from contrasting geochemistry of mafic and ultramafic orthogneisses in the Chochocouane River area, Quebec." Canadian Journal of Earth Sciences 42, no. 10 (October 1, 2005): 1653–75. http://dx.doi.org/10.1139/e05-068.
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Mafic and ultramafic orthogneisses from the western Grenville Province of Quebec adjacent to the Archean Superior Province (Canada) display geochemical characteristics that highlight processes that shaped the pre-Grenvillian Laurentian margin through late Archean to Mesoproterozoic time. Group I mafic and ultramafic granulites of the Parautochthonous Belt compositions overlap Archean Abitibi metavolcanic rocks (komatiites to Fe-rich andesites) supporting their autochthonous character. Limited variation of incompatible trace-element ratios with increasing differentiation suggests minimal sialic crust assimilation during petrogenesis and probable formation in an oceanic setting. Group II mafic tholeiites occur within both the Parautochthonous Belt and the Allochthonous Polycyclic Belt. Their compositions differ significantly from those of Archean rocks but overlap those of Proterozoic and modern continental tholeiites. Group III mafic calc-alkaline amphibolites, predominantly in the Allochthonous Polycyclic Belt, display chemical characteristics expected of magma derivation from subducted oceanic crust. In contrast to group I Archean meta-igneous rocks metamorphosed during the Kenoran orogeny, group III rocks do not record an early phase of large-ion lithophile element (LILE) metasomatism and granulite-facies metamorphism. As such, their emplacement is interpreted to postdate the Archean Kenoran metamorphism and to be Proterozoic in age. Group I rocks reflect an Archaean ensimatic greenstone belt environment; group II tholeiites reflect a Proterozoic continental rift environment; and group III rocks reflect a subduction-related source, possibly related to Andean-style, calc-alkaline magmatism.
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Woodson, Jesse D., Carmen L. Zayas, and Jorge C. Escalante-Semerena. "A New Pathway for Salvaging the CoenzymeB12 Precursor Cobinamide in Archaea RequiresCobinamide-Phosphate Synthase (CbiB) EnzymeActivity." Journal of Bacteriology 185, no. 24 (December 15, 2003): 7193–201. http://dx.doi.org/10.1128/jb.185.24.7193-7201.2003.
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ABSTRACT The ability of archaea to salvage cobinamide has been under question because archaeal genomes lack orthologs to the bacterial nucleoside triphosphate:5′-deoxycobinamide kinase enzyme (cobU in Salmonella enterica). The latter activity is required for cobinamide salvaging in bacteria. This paper reports evidence that archaea salvage cobinamide from the environment by using a pathway different from the one used by bacteria. These studies demanded the functional characterization of two genes whose putative function had been annotated based solely on their homology to the bacterial genes encoding adenosylcobyric acid and adenosylcobinamide-phosphate synthases (cbiP and cbiB, respectively) of S. enterica. A cbiP mutant strain of the archaeon Halobacterium sp. strain NRC-1 was auxotrophic for adenosylcobyric acid, a known intermediate of the de novo cobamide biosynthesis pathway, but efficiently salvaged cobinamide from the environment, suggesting the existence of a salvaging pathway in this archaeon. A cbiB mutant strain of Halobacterium was auxotrophic for adenosylcobinamide-GDP, a known de novo intermediate, and did not salvage cobinamide. The results of the nutritional analyses of the cbiP and cbiB mutants suggested that the entry point for cobinamide salvaging is adenosylcobyric acid. The data are consistent with a salvaging pathway for cobinamide in which an amidohydrolase enzyme cleaves off the aminopropanol moiety of adenosylcobinamide to yield adenosylcobyric acid, which is converted by the adenosylcobinamide-phosphate synthase enzyme to adenosylcobinamide-phosphate, a known intermediate of the de novo biosynthetic pathway. The existence of an adenosylcobinamide amidohydrolase enzyme would explain the lack of an adenosylcobinamide kinase in archaea.
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BOGATYREVA, NATALYA S., ALEXEI V. FINKELSTEIN, and OXANA V. GALZITSKAYA. "TREND OF AMINO ACID COMPOSITION OF PROTEINS OF DIFFERENT TAXA." Journal of Bioinformatics and Computational Biology 04, no. 02 (April 2006): 597–608. http://dx.doi.org/10.1142/s0219720006002016.
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Archaea, bacteria and eukaryotes represent the main kingdoms of life. Is there any trend for amino acid compositions of proteins found in full genomes of species of different kingdoms? What is the percentage of totally unstructured proteins in various proteomes? We obtained amino acid frequencies for different taxa using 195 known proteomes and all annotated sequences from the Swiss–Prot data base. Investigation of the two data bases (proteomes and Swiss–Prot) shows that the amino acid compositions of proteins differ substantially for different kingdoms of life, and this difference is larger between different proteomes than between different kingdoms of life. Our data demonstrate that there is a surprisingly small selection for the amino acid composition of proteins for higher organisms (eukaryotes) and their viruses in comparison with the "random" frequency following from a uniform usage of codons of the universal genetic code. On the contrary, lower organisms (bacteria and especially archaea) demonstrate an enhanced selection of amino acids. Moreover, according to our estimates, 12%, 3% and 2% of the proteins in eukaryotic, bacterial and archaean proteomes are totally disordered, and long (> 41 residues) disordered segments are found to occur in 16% of arhaean, 20% of eubacterial and 43% of eukaryotic proteins for 19 archaean, 159 bacterial and 17 eukaryotic proteomes, respectively. A correlation between amino acid compositions of proteins of various taxa, show that the highest correlation is observed between eukaryotes and their viruses (the correlation coefficient is 0.98), and bacteria and their viruses (the correlation coefficient is 0.96), while correlation between eukaryotes and archaea is 0.85 only.
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Dobro, Megan J., Rachel Y. Samson, Zhiheng Yu, John McCullough, H. Jane Ding, Parkson Lee-Gau Chong, Stephen D. Bell, and Grant J. Jensen. "Electron cryotomography of ESCRT assemblies and dividing Sulfolobus cells suggests that spiraling filaments are involved in membrane scission." Molecular Biology of the Cell 24, no. 15 (August 2013): 2319–27. http://dx.doi.org/10.1091/mbc.e12-11-0785.
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The endosomal-sorting complex required for transport (ESCRT) is evolutionarily conserved from Archaea to eukaryotes. The complex drives membrane scission events in a range of processes, including cytokinesis in Metazoa and some Archaea. CdvA is the protein in Archaea that recruits ESCRT-III to the membrane. Using electron cryotomography (ECT), we find that CdvA polymerizes into helical filaments wrapped around liposomes. ESCRT-III proteins are responsible for the cinching of membranes and have been shown to assemble into helical tubes in vitro, but here we show that they also can form nested tubes and nested cones, which reveal surprisingly numerous and versatile contacts. To observe the ESCRT–CdvA complex in a physiological context, we used ECT to image the archaeon Sulfolobus acidocaldarius and observed a distinct protein belt at the leading edge of constriction furrows in dividing cells. The known dimensions of ESCRT-III proteins constrain their possible orientations within each of these structures and point to the involvement of spiraling filaments in membrane scission.
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Salvador-Castell, Marta, Maxime Tourte, and Philippe M. Oger. "In Search for the Membrane Regulators of Archaea." International Journal of Molecular Sciences 20, no. 18 (September 9, 2019): 4434. http://dx.doi.org/10.3390/ijms20184434.
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Membrane regulators such as sterols and hopanoids play a major role in the physiological and physicochemical adaptation of the different plasmic membranes in Eukarya and Bacteria. They are key to the functionalization and the spatialization of the membrane, and therefore indispensable for the cell cycle. No archaeon has been found to be able to synthesize sterols or hopanoids to date. They also lack homologs of the genes responsible for the synthesis of these membrane regulators. Due to their divergent membrane lipid composition, the question whether archaea require membrane regulators, and if so, what is their nature, remains open. In this review, we review evidence for the existence of membrane regulators in Archaea, and propose tentative location and biological functions. It is likely that no membrane regulator is shared by all archaea, but that they may use different polyterpenes, such as carotenoids, polyprenols, quinones and apolar polyisoprenoids, in response to specific stressors or physiological needs.
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Ozersky, D. A., and A. I. Orlova. "Strength Characteristics of Rock and their Analysis in the Construction Safety Assessment of Underground URF Structures." Radioactive Waste 22, no. 1 (2023): 70–76. http://dx.doi.org/10.25283/2587-9707-2023-1-70-76.
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The paper evaluates the hypothesis regarding potential application of testing results focused on physical and mechanical properties of well cores stored in an air-dry state to the safety assessment of underground URF structures with open arches. It also presents approaches to the categorization of the Archean gneisses at the Yeniseiskiy site according to the strength characteristics.
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Greenough, John D., and Kevin MacKenzie. "Igneous Rock Associations 18. Transition Metals in Oceanic Island Basalt: Relationships with the Mantle Components." Geoscience Canada 42, no. 3 (July 29, 2015): 351. http://dx.doi.org/10.12789/geocanj.2015.42.071.
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Incompatible elements and isotopic ratios identify three end-member mantle components in oceanic island basalt (OIB); EM1, EM2, and HIMU. We estimate compatible to mildly incompatible transition metal abundance trends (Ni, Co, Fe, Cu, Cr, V, Mn, Sc, and Zn) in “primitive” basalt suites (Mg# = Mg/(Mg + 0.9*Fe) atomic = 0.72) from 12 end-member oceanic islands by regressing metals against Fe/Mg ratios in sample suites, and solving for concentrations at Mg/Fe = 1 (Mg# = 0.72). Using the transition metal estimates, exploratory statistics reveal that islands ‘group’ based on mantle component type even when La/Yb ratios are used to compensate metal concentrations for percentage melting. Higher chalcophile Zn (and Pb, earlier work) in EM1 and EM2 compared to HIMU, and higher Cr (3+) and Sc in HIMU relative to EM1, support views that HIMU represents subduction-processed ocean floor basalt. Incompatible elements, ratios and isotopes indicate that EM1 is Archean, EM2 is Proterozoic or younger, and both are related to sediment subduction. As found with incompatible elements, EM1 and EM2 show similar ‘compatible’ element concentrations, but lower (multi-valence) Cr, Fe and Mn in EM1 could indirectly reflect increasing oxidation of subducted sediment between the Archean and Proterozoic. Alternatively, changes in subduction processes that yielded peak continental formation in the Neoarchean, and craton-suturing in the Paleoproterozoic may account for EM1–EM2 differences. EM1 shows similar or lower Cr, Ni and Co compared to HIMU and EM2 suggesting that economic viability of layered intrusions, which have extreme EM1-like signatures, is unrelated to high metals in EM1 mantle sources, but that high % melting appears important. Because core-concentrated transition metals correlate with mantle component type, lithospheric recycling apparently controls their concentrations in OIB and core-mantle interaction may be unimportant.RÉSUMÉLes éléments incompatibles et les rapports isotopiques permettent de délimiter trois termes extrêmes de composants mantéliques dans des basaltes insulaires océaniques (OIB), soit EM1, EM2, et HIMU. Nous estimons les tendances d’abondance de métaux de transition (Ni, Co, Fe, Cu, Cr, V, Mn, Sc, and Zn) compatibles à modérément incompatibles dans des suites de basaltes « primitifs » (Mg# = Mg/(Mg + 0,9*Fe) rayon atomique = 0,72) sur 12 termes extrêmes de matériaux insulaires océaniques, par régression des concentrations des métaux sur les rapports Fe/Mg dans des échantillons des suites, la détermination étant définie au rapport Mg/Fe = 1 (Mg# = 0,72). L’utilisation d’une approche statistique exploratoire sur les estimations de métaux de transition montre que la composition des îles se « regroupent » en fonction du type de composition du manteau, cela même lorsque les ratios La/Yb sont utilisés pour compenser les concentrations de métaux pour déterminer le pourcentuel de fusion. Le caractère plus chalcophile du Zn (et Pb, travail antérieur) dans EM1 et EM2 comparé à HIMU, et la plus grande teneur en Cr (3+) et Sc dans HIMU par rapport à EM1, accréditent l’idée que HIMU représente le basalte de subduction des fonds océaniques. Les éléments incompatibles, les ratios et les isotopes montrent que EM1 est archéen, que EM2 est protérozoïque ou plus jeune, et que les deux sont liés à la subduction sédimentaire. Comme constaté pour les éléments incompatibles, EMI et EM2 affichent une compatibilité similaire des concentrations en éléments « compatibles », toutefois une concentration inférieure en Cr (multivalent), Fe et Mn dans EM1 pourrait refléter indirectement une oxydation croissante des sédiments subduits entre l’Archéen et le Protérozoïque. Par ailleurs, les changements dans les mécanismes de subduction qui ont mené à un maximum de formation continentale au Néoarchéen et à des épisodes de sutures cratoniques au Paléoprotérozoïque, peuvent expliquer les différences entre EM1 et EM2. La teneur similaire ou inférieure en Cr, Ni et Co de EM1 par rapport à HIMU et EM2 permet de croire que la viabilité économique des intrusions stratifiées – lesquelles montrent des signatures extrêmes EM1 – est sans rapport avec les sources mantéliques à fortes teneurs en métaux, mais que le fort pourcentuel de fusion qui importerait. Parce que la concentration du noyau en métaux de transition correspond avec le type de composant du manteau, c’est le recyclage lithosphérique qui contrôle apparemment leurs concentrations dans l'OIB, et l'interaction noyau-manteau pourrait être sans importance.
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Cattani, Carlo. "On the Existence of Wavelet Symmetries in Archaea DNA." Computational and Mathematical Methods in Medicine 2012 (2012): 1–21. http://dx.doi.org/10.1155/2012/673934.
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This paper deals with the complex unit roots representation of archea DNA sequences and the analysis of symmetries in the wavelet coefficients of the digitalized sequence. It is shown that even for extremophile archaea, the distribution of nucleotides has to fulfill some (mathematical) constraints in such a way that the wavelet coefficients are symmetrically distributed, with respect to the nucleotides distribution.
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Jansson, B. P. Mattias, Laurence Malandrin, and Hans E. Johansson. "Cell Cycle Arrest in Archaea by the Hypusination Inhibitor N1-Guanyl-1,7-Diaminoheptane." Journal of Bacteriology 182, no. 4 (February 15, 2000): 1158–61. http://dx.doi.org/10.1128/jb.182.4.1158-1161.2000.
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ABSTRACT Hypusination is an essential posttranslational modification unique to archaeal and eukaryotic protein synthesis initiation factor 5A (aIF5A and eIF5A, respectively). We have investigated the effect of the efficient hypusination inhibitorN 1-guanyl-1,7-diaminoheptane (GC7) on four archaeal and one bacterial species. We found that (i) archaea are sensitive to GC7, whereas the bacteriumEscherichia coli is not, (ii) GC7 causes rapid and reversible arrest of growth of the archaeon Sulfolobus acidocaldarius, and (iii) the growth arrest is accompanied by a specific reversible arrest of the cell cycle prior to cell division. Our findings establish a link between hypusination and sustained growth of archaea and thereby provide the framework to study molecular details of archaeal cell cycle in connection with in vivo functions of hypusine and of aIF5A and eIF5A.
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Ilina, Larisa, Valentina Filippova, Elena Yildirim, and Kasim Layshev. "Archaea in the microbial community of the reindeer rumen in the Russian Arctic." BIO Web of Conferences 27 (2020): 00066. http://dx.doi.org/10.1051/bioconf/20202700066.
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Archaea is the least studied group of the reindeer rumen microbiocenosis. Although the functional load performed by this group of microorganisms in the rumen is large. Methane-forming archaea play a key role in the process of anaerobic decomposition of organic substances, the formation of methane. This study for the first time analyzed the composition of the archaeal part of the microbial community of the reindeer rumen using the T-RFLP method from various regions of the Russian Arctic. As a result, it was found that according to the estimates of the number of archaea by quantitative PCR in the reindeer rumen in the winter-spring period, on average, 108 genomes/g of archaea were observed in individuals of the Yamalo-Nenets Autonomous District, and 109 genomes/in animals from the Nenets Autonomous District Archean. Thus, in the winter-spring period, a lower number of archaea in the rumen was observed in the Yamalo-Nenets Autonomous District. According to the results of the T-RFLP method, 44 to 134 phylotypes were detected in the archaeal community of the reindeer rumen, the Shannon index was 2.02–3.80. The lowest content (up to 11.10 %) of methanogenic archaea of the Methanomicrobia class (including the families Methanosarcinaceae and Methanocorpusculaceae) was revealed in the Nenets Autonomous District, while their presence in individuals of the Yamalo-Nenets Autonomous District reached 36.33 %. Interestingly, in adults of the Yamalo-Nenets and Nenets Autonomous Districts, a significant decrease in the representation of methanogenic archaea of the Methanomicrobia class was noted by 1.38 (P <0.05) and 2.70 times (P <0.01), respectively, compared with young individuals (up to 2 years).
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Liu, Yuchen, David J. Vinyard, Megan E. Reesbeck, Tateki Suzuki, Kasidet Manakongtreecheep, Patrick L. Holland, Gary W. Brudvig, and Dieter Söll. "A [3Fe-4S] cluster is required for tRNA thiolation in archaea and eukaryotes." Proceedings of the National Academy of Sciences 113, no. 45 (October 24, 2016): 12703–8. http://dx.doi.org/10.1073/pnas.1615732113.
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The sulfur-containing nucleosides in transfer RNA (tRNAs) are present in all three domains of life; they have critical functions for accurate and efficient translation, such as tRNA structure stabilization and proper codon recognition. The tRNA modification enzymes ThiI (in bacteria and archaea) and Ncs6 (in archaea and eukaryotic cytosols) catalyze the formation of 4-thiouridine (s4U) and 2-thiouridine (s2U), respectively. The ThiI homologs were proposed to transfer sulfur via cysteine persulfide enzyme adducts, whereas the reaction mechanism of Ncs6 remains unknown. Here we show that ThiI from the archaeon Methanococcus maripaludis contains a [3Fe-4S] cluster that is essential for its tRNA thiolation activity. Furthermore, the archaeal and eukaryotic Ncs6 homologs as well as phosphoseryl-tRNA (Sep-tRNA):Cys-tRNA synthase (SepCysS), which catalyzes the Sep-tRNA to Cys-tRNA conversion in methanogens, also possess a [3Fe-4S] cluster similar to the methanogenic archaeal ThiI. These results suggest that the diverse tRNA thiolation processes in archaea and eukaryotic cytosols share a common mechanism dependent on a [3Fe-4S] cluster for sulfur transfer.
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Ayiti, Oluwatobi Esther, Ayansina Segun Ayangbenro, and Olubukola Oluranti Babalola. "16S Amplicon Sequencing of Nitrifying Bacteria and Archaea Inhabiting Maize Rhizosphere and the Influencing Environmental Factors." Agriculture 12, no. 9 (August 28, 2022): 1328. http://dx.doi.org/10.3390/agriculture12091328.
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Nitrifying bacteria and archaea are ubiquitous and can transform ammonia locked up in soil or manure into nitrate, a more soluble form of nitrogen. However, nitrifying bacteria and archaea inhabiting maize rhizosphere have not been fully explored. This study evaluates the diversity and abundance of nitrifying bacteria and archaea across different growth stages of maize using 16S amplicon sequencing. Moreover, the influence of environmental factors (soil physical and chemical properties) on the nitrifying communities was evaluated. Rhizosphere soil DNA was extracted using Nucleospin Soil DNA extraction kit and sequenced on Illumina Miseq platform. MG-RAST was used to analyze the raw sequences. The physical and chemical properties of the soil were measured using standard procedure. The results revealed 9 genera of nitrifying bacteria; Nitrospira, Nitrosospira, Nitrobacter, Nitrosovibrio, Nitrosomonas, Nitrosococcus, Nitrococcus, unclassified (derived from Nitrosomonadales), unclassified (derived from Nitrosomonadaceae) and 1 archaeon Candidatus Nitrososphaera. The Nitrospirae phyla group, which had the most nitrifying bacteria, was more abundant at the tasselling stage (67.94%). Alpha diversity showed no significant difference. However, the Beta diversity showed significant difference (p = 0.01, R = 0.58) across the growth stages. The growth stages had no significant effect on the diversity of nitrifying bacteria and archaea, but the tasselling stage had the most abundant nitrifying bacteria. A correlation was observed between some of the chemical properties and some nitrifying bacteria. The research outcome can be put into consideration while carrying out a biotechnological process that involves nitrifying bacteria and archaea.
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Meyer, Benjamin H., and Sonja-Verena Albers. "Hot and sweet: protein glycosylation in Crenarchaeota." Biochemical Society Transactions 41, no. 1 (January 29, 2013): 384–92. http://dx.doi.org/10.1042/bst20120296.
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Every living cell is covered with a dense and complex array of covalently attached sugars or sugar chains. The majority of these glycans are linked to proteins via the so-called glycosylation process. Protein glycosylation is found in all three domains of life: Eukarya, Bacteria and Archaea. However, on the basis of the limit in analytic tools for glycobiology and genetics in Archaea, only in the last few years has research on archaeal glycosylation pathways started mainly in the Euryarchaeota Haloferax volcanii, Methanocaldococcus maripaludis and Methanococcus voltae. Recently, major steps of the crenarchaeal glycosylation process of the thermoacidophilic archaeon Sulfolobus acidocaldarius have been described. The present review summarizes the proposed N-glycosylation pathway of S. acidocaldarius, describing the phenotypes of the mutants disrupted in N-glycan biosynthesis as well as giving insights into the archaeal O-linked and glycosylphosphatidylinositol anchor glycosylation process.
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Pubali Das, Jeyakumar. S, Annie Thomas, and Priti Lendghar. "Correlation between Foot Transverse Arch Index and Foot Posture Index in Identifying Foot Arches in Healthy Population." Indian Journal of Physiotherapy & Occupational Therapy - An International Journal 18 (January 21, 2024): 942–47. http://dx.doi.org/10.37506/3gw18f74.
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Background: Medial longitudinal arch of foot plays a crucial role on maintaining ankle during weight bearing activities. In previous studies arch index derived from foot print shows a negative correlation with the navicular height. There are no other studies have correlated mathematically derived foot print values with standing arch height measurements with an acceptable equation. This study correlates arch index and foot posture index to identify foot arches. Methods: subjects with high arch have taken for the study. The study type is observational study was done on sample size n=60,foot arch index and foot posture index was evaluated with the samples. Findings: a r- value of 0.333, there is a Negative correlation between Arch index and Foot posture index in low arched foot. There is no significant correlation, and the a r- value of 0.173, there is a low positive correlation between arch index and foot posture index in high arched foot. Interpretation: Among high arched foot and low arched foot, Foot Posture Index and Arch Index is correlated, according to Pearson's correlation, only high arched foot shows low positive correlation between Foot Posture Index and Arch Index. Flatfoot shows negative correlation.
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Trudel, Pierre. "Recent developments in the study of Archean gold deposits Développements récents dans l'étude des gisements d'or archéens." Canadian Journal of Earth Sciences 27, no. 12 (December 1, 1990): 1557–59. http://dx.doi.org/10.1139/e90-167.
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Shestakov, Sergey V. "The role of archaea in the origin of eukaryotes." Ecological genetics 15, no. 4 (December 25, 2017): 52–59. http://dx.doi.org/10.17816/ecogen15452-59.
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A key role of particular evolutionary branch of archaea in the emergence of eukaryotic cell is considered on the basis of phylogenomics. Genomes of recently discovered uncultivated proteoarchaea belonging to Lokiarchaea and Asgard-group contain a large sets of eukaryotic-like genes. This allows to suggest that ancient forms of such archaean could participate in symbiotic fusion with bacteria serving as a mitochondrial progenitor. The open questions concerning properties of LECA (so-called last eukaryotic common ancestor) are discussed in the frame of endosymbiotic hypothesis of eukaryogenesis.
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Wang, Yinzhao, Ruize Xie, Jialin Hou, Zhenbo Lv, Liuyang Li, Yaoxun Hu, Hungchia Huang, and Fengping Wang. "The late Archaean to early Proterozoic origin and evolution of anaerobic methane‐oxidizing archaea." mLife 1, no. 1 (March 2022): 96–100. http://dx.doi.org/10.1002/mlf2.12013.
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Ventura, G. T., F. Kenig, C. M. Reddy, J. Schieber, G. S. Frysinger, R. K. Nelson, E. Dinel, R. B. Gaines, and P. Schaeffer. "Molecular evidence of Late Archean archaea and the presence of a subsurface hydrothermal biosphere." Proceedings of the National Academy of Sciences 104, no. 36 (August 28, 2007): 14260–65. http://dx.doi.org/10.1073/pnas.0610903104.
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Chow, Tong-Hsien, Yih-Shyuan Chen, and Jia-Chang Wang. "Characteristics of Plantar Pressures and Related Pain Profiles in Elite Sprinters and Recreational Runners." Journal of the American Podiatric Medical Association 108, no. 1 (January 1, 2018): 33–44. http://dx.doi.org/10.7547/15-189.
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Background: Plantar pressure measurement is effective for assessing plantar loading and can be applied to evaluating foot performance. We sought to explore the characteristics of plantar pressures in elite sprinters and recreational runners during static standing and walking. Methods: Arch index (AI) values, regional plantar pressure distributions (PPDs), and footprint characteristics were examined in 80 elite sprinters and 90 recreational runners using an optical plantar pressure measurement system. Elite sprinters' pain profiles were examined to evaluate their most common pain areas. Results: In recreational runners, AI values in males were in the normal range and in females were high arch type. The AI values were significantly lower in elite sprinters than in recreational runners. In elite sprinters, particularly males, the static PPD of both feet was higher at the medial metatarsal bone and the lateral heel and lower at the medial and lateral longitudinal arches. Elite male sprinters' PPD of both feet was mainly transferred to the medial metatarsal bone and decreased at the lateral longitudinal arch and the medial heel during the midstance phase of walking. The lateral knee joint and biceps femoris were the most common sites of musculoskeletal pain in elite sprinters. Conclusions: Elite sprinters' AI values could be classified as high arches, and their PPD tended to parallel the features of runners and high-arched runners. These findings correspond to the profile of patellofemoral pain syndrome (PFPS)–related plantar pressure. The pain profiles seemed to resonate with the symptoms of high-arched runners and PFPS. A possible link between high-arched runners and PFPS warrants further study.
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Cui, Kai, Jun Feng, and Chengyong Zhu. "A Study on the Mechanisms of Interaction between Deep Foundation Pits and the Pile Foundations of Adjacent Skewed Arches as well as Methods for Deformation Control." Complexity 2018 (2018): 1–19. http://dx.doi.org/10.1155/2018/6535123.
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The construction of deep foundation pits is characterized by heavy loads on pile foundations, complex interactions between the foundation pit and pile foundations, and stringent requirements for deformation control. In this work, FLAC3D was used to perform computational analyses on the displacement responses of pile caps and the retaining walls of foundation pits in a variety of cases and reinforcement schemes. The computational results indicate that the piles of skewed arches interact with the retaining walls of the foundation pits through soil masses. We also revealed the mechanism by which deep foundation pits interacted with the pile foundations of adjacent skewed arches. Based on the mechanisms of interaction between foundation pit excavations and the piles of skewed arches, we proposed three reinforcement schemes for controlling the deformations associated with these interactions. The arched wall reinforcement scheme could provide a satisfactory result in terms of the control of horizontal displacements in the pile foundations and project costs.
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Ishibashi, Yumi, Natsumi Matsushima, Tomokazu Ito, and Hisashi Hemmi. "Isopentenyl diphosphate/dimethylallyl diphosphate-specific Nudix hydrolase from the methanogenic archaeon Methanosarcina mazei." Bioscience, Biotechnology, and Biochemistry 86, no. 2 (December 1, 2021): 246–53. http://dx.doi.org/10.1093/bbb/zbab205.
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ABSTRACT Nudix hydrolases typically catalyze the hydrolysis of nucleoside diphosphate linked to moiety X and yield nucleoside monophosphate and X-phosphate, while some of them hydrolyze a terminal diphosphate group of non-nucleosidic compounds and convert it into a phosphate group. Although the number of Nudix hydrolases is usually limited in archaea comparing with those in bacteria and eukaryotes, the physiological functions of most archaeal Nudix hydrolases remain unknown. In this study, a Nudix hydrolase family protein, MM_2582, from the methanogenic archaeon Methanosarcina mazei was recombinantly expressed in Escherichia coli, purified, and characterized. This recombinant protein shows higher hydrolase activity toward isopentenyl diphosphate and short-chain prenyl diphosphates than that toward nucleosidic compounds. Kinetic studies demonstrated that the archaeal enzyme prefers isopentenyl diphosphate and dimethylallyl diphosphate, which suggests its role in the biosynthesis of prenylated flavin mononucleotide, a recently discovered coenzyme that is required, for example, in the archaea-specific modified mevalonate pathway.
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Blombach, Fabian, Stan J. J. Brouns, and John van der Oost. "Assembling the archaeal ribosome: roles for translation-factor-related GTPases." Biochemical Society Transactions 39, no. 1 (January 19, 2011): 45–50. http://dx.doi.org/10.1042/bst0390045.
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The assembly of ribosomal subunits from their individual components (rRNA and ribosomal proteins) requires the assistance of a multitude of factors in order to control and increase the efficiency of the assembly process. GTPases of the TRAFAC (translation-factor-related) class constitute a major type of ribosome-assembly factor in Eukaryota and Bacteria. They are thought to aid the stepwise assembly of ribosomal subunits through a ‘molecular switch’ mechanism that involves conformational changes in response to GTP hydrolysis. Most conserved TRAFAC GTPases are involved in ribosome assembly or other translation-associated processes. They typically interact with ribosomal subunits, but in many cases, the exact role that these GTPases play remains unclear. Previous studies almost exclusively focused on the systems of Bacteria and Eukaryota. Archaea possess several conserved TRAFAC GTPases as well, with some GTPase families being present only in the archaeo–eukaryotic lineage. In the present paper, we review the occurrence of TRAFAC GTPases with translation-associated functions in Archaea.
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Denis, Antonia, Mario Alberto Martínez-Núñez, Silvia Tenorio-Salgado, and Ernesto Perez-Rueda. "Dissecting the Repertoire of DNA-Binding Transcription Factors of the Archaeon Pyrococcus furiosus DSM 3638." Life 8, no. 4 (September 21, 2018): 40. http://dx.doi.org/10.3390/life8040040.
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In recent years, there has been a large increase in the amount of experimental evidence for diverse archaeal organisms, and these findings allow for a comprehensive analysis of archaeal genetic organization. However, studies about regulatory mechanisms in this cellular domain are still limited. In this context, we identified a repertoire of 86 DNA-binding transcription factors (TFs) in the archaeon Pyrococcus furiosus DSM 3638, that are clustered into 32 evolutionary families. In structural terms, 45% of these proteins are composed of one structural domain, 41% have two domains, and 14% have three structural domains. The most abundant DNA-binding domain corresponds to the winged helix-turn-helix domain; with few alternative DNA-binding domains. We also identified seven regulons, which represent 13.5% (279 genes) of the total genes in this archaeon. These analyses increase our knowledge about gene regulation in P. furiosus DSM 3638 and provide additional clues for comprehensive modeling of transcriptional regulatory networks in the Archaea cellular domain.