The universal ancestor : an unfinished reconstruction

The cenancestor is defined as the last common ancestor of every currently living being. Its nature has been inferred from the identification of homologous genes between archaea, bacteria, and eukaryotic lineages. These inferences indicate that the cenancestor had a relatively modern protein translation system, similar in complexity to that of a current cell. However, the key enzymes for the replication of genetic material and for cell membrane biosynthesis are not homologous in bacteria, archaea, and eukaryotes. Here, we briefly review the history of the concept of the last universal common ancestor and the different hypotheses proposed for its biology

The origin of a novel gene through overprinting in Escherichia coli

<p>Abstract</p> <p>Background</p> <p>Overlapped genes originate by a) loss of a stop codon among contiguous genes coded in different frames; b) shift to an upstream initiation codon of one of the contiguous genes; or c) by overprinting, whereby a novel open reading frame originates through point mutation inside an existing gene. Although overlapped genes are common in viruses, it is not clear whether overprinting has led to new genes in prokaryotes.</p> <p>Results</p> <p>Here we report the origin of a new gene through overprinting in <it>Escherichia coli </it>K12. The <it>htgA </it>gene coding for a positive regulator of the sigma 32 heat shock promoter arose by point mutation in a 123/213 phase within an open reading frame (<it>yaaW</it>) of unknown function, most likely in the lineage leading to <it>E. coli </it>and <it>Shigella sp</it>. Further, we show that <it>yaaW </it>sequences coding for <it>htgA </it>genes have a slower evolutionary rate than those lacking an overlapped <it>htgA </it>gene.</p> <p>Conclusion</p> <p>While overprinting has been shown to be rather frequent in the evolution of new genes in viruses, our results suggest that this mechanism has also contributed to the origin of a novel gene in a prokaryote. We propose the term <it>janolog </it>(from <it>Jano</it>, the two-faced Roman god) to describe the homology relationship that holds between two genes when one originated through overprinting of the other. One cannot dismiss the possibility that at least a small fraction of the large number of novel ORPhan genes detected in pan-genome and metagenomic studies arose by overprinting.</p

Comparative biochemistry of CO2 fixation and the evolution of autotrophy

Carbon dioxide fixation is a polyphyletic trait that has evolved in widely separated prokaryotic branches. The three principal CO2-assimilation pathways are (i) the reductive pentose-phosphate cycle, i. e. the Calvin-Benson cycle; (ii) the reductive citric acid (or Arnon) cycle; and (iii) the net synthesis of acetyl-CoA from CO/CO2, or Wood pathway. Sequence analysis and the comparative biochemistry of these routes suggest that all of them were shaped to a considerable extent by the evolutionary recruitment of enzymes. Molecular phylogenetic trees show that the Calvin-Benson cycle was a relatively late development in the (eu)bacterial branch, suggesting that some form(s) of carbon assimilation may have been operative before chlorophyll-based photosynthesis. On the other hand, the ample phylogenetic distribution of both the Arnon and the Wood pathways does not allow us to infer which one of them is older. However, different lines of evidence, including experimental reports on the NiS/FeS-mediated C–C bond formation from CO and CH3SH are used here to argue that the first CO2-fixation route may have been a semienzymatic Wood-like [email protected]

Las microformas digitales y su relación con los procesos técnicos archivísticos en una unidad de gestión documental estatal, Lima 2022

La investigación “Las Microformas digitales y su relación con los Procesos técnicos archivísticos en una Unidad de Gestión Documental estatal, Lima 2022” tiene como objetivo de investigación el determinar el grado de relación que existe entre las Microformas Digitales y los Procesos Técnicos Archivísticos, a través del uso de instrumentos que permitirán establecer la medida del grado de relación entre las variables. Para el desarrollo de la presente investigación se usó el estudio de diseño no experimental de corte transversal con un nivel correlacional de tipo aplicada para una población de 42 servidores públicos (100%) que laboran en las diversas áreas que conforman la oficina de la Unidad de Gestión Documental de la Superintendencia Nacional de Migraciones. En esta investigación se empleó como instrumento de medición el cuestionario, el cual fue debidamente validado por expertos. Con el fin de medir la relación entre las microformas digitales y los procesos técnicos archivísticos. La investigación concluye en lo siguiente existe relación significativa entre las Microformas digitales y los procesos Técnicos Archivísticos de la unidad de Gestión documental de la superintendencia nacional de Migraciones-2022. Lo cual se pudo verificar con la prueba de Spearman (sig. bilateral = .000 < 0.05; Rho= ,592**)

Research and Development in the School of Technologies of the Catholic University of Colombia

The current article is intended to bring to notice the process which allowed for the outlining of Applied and Technological research at the School of technologies of the Catholic University of Colombia. This subsystem of research is characterized by overlapping all academic programs, research focuses, research groups, research practices, degree works, research projects and all scientific outreaching eventsEl objetivo de este artículo es divulgar el proceso que originó la reestructuración de los lineamientos de investigación aplicada y tecnológica en la Escuela de Tecnologías de la Universidad Católica de Colombia. Este subsistema de investigación se caracteriza por vincular formalmente dentro de los programas académicos y alrededor de sus líneas de investigación, todos los agentes implicados en el desarrollo investigativo: semilleros y grupos de investigación, prácticas investigativas, trabajos de grado, proyectos de investigación, y eventos académicos de divulgación científic

Comparative biochemistry of CO2 fixation and the evolution of autotrophy

Carbon dioxide fixation is a polyphyletic trait that has evolved in widely separated prokaryotic branches. The three principal CO2-assimilation pathways are (i) the reductive pentose-phosphate cycle, i. e. the Calvin-Benson cycle; (ii) the reductive citric acid (or Arnon) cycle; and (iii) the net synthesis of acetyl-CoA from CO/CO2, or Wood pathway. Sequence analysis and the comparative biochemistry of these routes suggest that all of them were shaped to a considerable extent by the evolutionary recruitment of enzymes. Molecular phylogenetic trees show that the Calvin-Benson cycle was a relatively late development in the (eu)bacterial branch, suggesting that some form(s) of carbon assimilation may have been operative before chlorophyll-based photosynthesis. On the other hand, the ample phylogenetic distribution of both the Arnon and the Wood pathways does not allow us to infer which one of them is older. However, different lines of evidence, including experimental reports on the NiS/FeS-mediated C–C bond formation from CO and CH3SH are used here to argue that the first CO2-fixation route may have been a semienzymatic Wood-like pathway

Hyperthermophily and the origin and earliest evolution of life

The possibility of a high-temperature origin of life has gained support based on indirect evidence of a hot, early Earth and on the basal position of hyperthermophilic organisms in rRNA-based phylogenies. However, although the availability of more than 80 completely sequenced cellular genomes has led to the identification of hyperthermophilic-specific traits, such as a trend towards smaller genomes, reduced proteinencoding gene sizes, and glutamic-acid-rich simple sequences, none of these characteristics are in themselves an indication of primitiveness. There is no geological evidence for the physical setting in which life arose, but current models suggest that the Earth’s surface cooled down rapidly. Moreover, at 100°C the half-lives of several organic compounds, including ribose, nucleobases, and amino acids, which are generally thought to have been essential for the emergence of the first living systems, are too short to allow for their accumulation in the prebiotic environment. Accordingly, if hyperthermophily is not truly primordial, then heat-loving lifestyles may be relics of a secondary adaptation that evolved after the origin of life, and before or soon after separation of the major lineages

Boletín de la Sociedad Geológica Mexicana Volumen 68

Abstract Hyperthermophilic organisms have been recognized as an important element in the origin and early evolution of life on Earth, but also as a model for exobiological studies. Analyzing their molecular dynamics can help us understand this important lifestyle. In this study, using bioinformatic tools, the DNA composition in chromosomes and plasmids of hyperthemophilic organism were compared, and their structure, probable amino acid bias and DNA flexibility were analyzed. In some chromosomes and plasmids shows differential features of DNA flexibility and skews in mutation rate, which suggests that only some molecular elements show high values of variability, contrary to the proposal of the flexible genome theory. Keywords: chromosome, plasmids, Quintana values, DNA twisting, codon usage, hyperthermophiles. Resumen Los organismos hipertermofílicos han sido reconocidos tanto como un elemento importante en el origen y la evolución temprana de la vida en la Tierra, como un modelo en estudios de exobiología. Analizar sus dinámicas moleculares nos puede ayudar a entende

A phylogenetic approach to the early evolution of autotrophy: the case of the reverse TCA and the reductive acetyl-CoA pathways

In recent decades, a number of hypotheses on the autotrophic origin of life have been presented. These proposals invoke the emergence of reaction networks leading from CO or CO2 to the organic molecules required for life. It has also been suggested that the last (universal) common ancestor (LCA or LUCA) of all extant cell lineages was a chemolitho-autotrophic thermophilic anaerobe. The antiquity of some carbon fixation pathways, the phylogenetic basal distribution of some autotrophic organisms, and the catalytic properties of iron-sulfur minerals have been advanced in support of these ideas. Here we critically examine the phylogenetic distribution and evolution of enzymes that are essential for two of the most ancient autotrophic means of metabolism: the reductive tricarboxylic acid (rTCA) cycle and the reductive acetyl-CoA pathway. Phylogenetic analysis of citryl-CoA synthetase and of citryl-CoA lyase, key enzymatic components of the rTCA cycle, and of CO dehydrogenase/acetyl-CoA synthase, a key enzyme in the reductive acetyl-CoA pathway, revealed that all three enzymes have undergone major lateral transfer events and therefore cannot be used as proof of the LCA&rsquo;s metabolic abilities nor as evidence of an autotrophic origin of life. [Int Microbiol 2014; 17(2):91-97]Keywords: autotrophic pathways &middot; reverse Krebs cycle &middot; Wood&ndash;Ljungdahl pathway &middot; origin of life &middot; last common ancestor (LCA, LUCA

Algunas consideraciones en torno a la restauración turística post terremoto de la ciudad de Manta, Manabí, Ecuador

This article aims to discuss strategies and actions for the restoration of Manta, a city that was impacted by the earthquake of April 16, 2016. Methodologically, it was addressed as a descriptive, documentary and field research, supported by bibliographic consultations and in the application of unstructured interviews with key informants who are part of those affected and who in turn are actors of local tourism in Manta. Part of the data was obtained directly from the source; with field observation, but also with consultation and review of diverse bibliographic material, among them, reports of the Council of Emergency Operations (COE) of the municipality; which allowed to have an approximation to the state in which the hotel was left after the occurrence of the earthquake. There is a need to implement a set of strategies and actions framed in a restoration plan in terms of tourism and hotel infrastructure, in order to attract a flow of visitors according to the new characteristics of the destination.Este artículo tiene como objetivo discutir estrategias y acciones para la restauración de Manta, ciudad que fue impactada por el terremoto del 16 de abril de 2016. Se abordó metodológicamente como una investigación descriptiva, documental y de campo, apoyada en consultas bibliográficas y en la aplicación de entrevistas no estructuradas a informantes clave que forman parte de los afectados y que a su vez son actores del turismo local de Manta. Parte de los datos fueron obtenidos directamente de la fuente; con observación de campo, pero también con la consulta y revisión de material bibliográfico diverso, entre ellos, informes del Consejo de Operaciones de Emergencia (COE) del municipio; lo cual permitió tener una aproximación al estado en que quedó la planta hotelera manteña posterior a la ocurrencia del sismo. Se plantea la necesidad de implementar un conjunto de estrategias y acciones enmarcadas en un plan de restauración en materia de infraestructura turística y hotelera, a los fines de atraer un flujo de visitantes acorde a las nuevas características del destino