Loss of Editing Activity During the Evolution of Mitochondrial Phenylalanyl-tRNA Synthetase

Accurate selection of amino acids is essential for faithful translation of the genetic code. Errors during amino acid selection are usually corrected by the editing activity of aminoacyl-tRNA synthetases such as phenylalanyl-tRNA synthetases (PheRS), which edit misactivated tyrosine. Comparison of cytosolic and mitochondrial PheRS from the yeast Saccharomyces cerevisiae suggested that the organellar protein might lack the editing activity. Yeast cytosolic PheRS was found to contain an editing site, which upon disruption abolished both cis and trans editing of Tyr-tRNAPhe. Wild-type mitochondrial PheRS lacked cis and trans editing and could synthesize Tyr-tRNAPhe, an activity enhanced in active site variants with improved tyrosine recognition. Possible trans editing was investigated in isolated mitochondrial extracts, but no such activity was detected. These data indicate that the mitochondrial protein synthesis machinery lacks the tyrosine proofreading activity characteristic of cytosolic translation. This difference between the mitochondria and the cytosol suggests that either organellar protein synthesis quality control is focused on another step or that translation in this compartment is inherently less accurate than in the cytosol

Experiencia comunitaria : la construcción del sujeto colectivo

Este proyecto surge de la potencia que intuimos en las iniciativas de gestión comunitaria como escenarios de reflexión, de producción de conocimiento, de re-significación de la vida y de la situación del país y de reconstrucción de una concepción del ser humano y de comunidad real y aterrizada en la experiencia que permite generar espacios de transformación social, política, económica, cultural y humana. El presente trabajo resulta pertinente para el ámbito de la psicología, pues a partir de la comprensión de los dispositivos de subjetivación política que se construyen en diferentes experiencias comunitarias y de cómo éstos configuran la noción de un sujeto colectivo, se contribuye al futuro planteamiento de modos alternativos de relaciones en ámbitos diferentes a comunidades. Para comprender formas alternativas de relación que puedan ampliar las posibilidades de acción y participación colectiva en los ámbitos que parecen estar completamente sujetos a la fragmentación social de la que se vale el capitalismo. De ahí que se pueda sostener que este proyecto puede aportar a la construcción de propuestas metodológicas en el campo de la psicología social, encaminadas a fortalecer el tejido social y así, a promover un mayor sentido de pertenencia y comunidad. Por otro lado, el presente trabajo de grado permite un diálogo con diversas investigaciones realizadas alrededor de las implicaciones y dinámicas que aparecen y participan de la consolidación de los procesos comunitarios. La presente investigación propone una mirada que enriquece la comprensión de las experiencias comunitarias, pues se aproxima a los procesos al interior de eco aldeas y experiencias comunitarias enfatizando en la acción de los dispositivos de subjetivación en el ámbito comunitario y colectivo, se decantan en una propuesta transformadora y en la posibilidad de constituirse como sujetos políticos construidos desde la colectividad.This project arises from the power that we intuit in community initiatives as scenarios for reflection, for the production of knowledge, for the re-signification of life and the situation of the country, and for the reconstruction of a conception of the human being and of the real community, grounded in the experience that allows generating spaces for social, political, economic, cultural and human transformation. The present work is relevant to the field of psychology, since from the understanding of the devices of political subjectivation that are constructed in different community experiences and how these configure the notion of a collective subject, the future approach is contributed to ways alternative relationships in areas other than communities. To understand alternative forms of relationship that can expand the possibilities of action and collective participation in areas that seem to be completely subject to the social fragmentation that capitalism uses. Hence, it can be argued that this project can contribute to the construction of methodological proposals in the field of social psychology, aimed at strengthening the social fabric and thus promoting a greater sense of belonging and community. On the other hand, the present work of degree allows a dialogue with various researches carried out around the implications and dynamics that appear and participate in the consolidation of community processes. The present research proposes a view that enriches the understanding of community experiences, as it approaches processes within ecovillages and community experiences, emphasizing the action of subjectivation devices in the community and collective sphere, they opt for a proposal transformative and in the possibility of constituting themselves as political subjects constructed from the collectivity.Psicólogo (a)Pregrad

Effects of Trypanosoma brucei tryptophanyl-tRNA synthetases silencing by RNA interference

The kinetoplast genetic code deviates from the universal code in that 90% of mitochondrial tryptophans are specified by UGA instead of UGG codons. A single nucleus-encoded tRNA Trp(CCA) is used by both nuclear and mitochondria genes, since all kinetoplast tRNAs are imported into the mitochondria from the cytoplasm. To allow decoding of the mitochondrial UGA codons as tryptophan, the tRNA Trp(CCA) anticodon is changed to UCA by an editing event. Two tryptophanyl tRNA synthetases (TrpRSs) have been identified in Trypanosoma brucei: TbTrpRS1 and TbTrpRS2 which localize to the cytoplasm and mitochondria respectively. We used inducible RNA interference (RNAi) to assess the role of TbTrpRSs. Our data validates previous observations of TrpRS as potential drug design targets and investigates the RNAi effect on the mitochondria of the parasite

C to U Editing Stimulates A to I Editing in the Anticodon Loop of a Cytoplasmic Threonyl tRNA in Trypanosoma brucei

Editing of tRNAs is widespread in nature and either changes the decoding properties or restores the folding of a tRNA. Unlike the phylogenetically disperse adenosine (A) to inosine (I) editing, cytosine (C) to uridine (U) editing has only been previously described in organellar tRNAs. We have shown that cytoplasmic tRNAThr(AGU) undergoes two distinct editing events in the anticodon loop: C to U and A to I. In vivo, every inosine-containing tRNAThr is also C to U edited at position 32. In vitro, C to U editing stimulates conversion of A to I at the wobble base. Although the in vivo and in vitro requirements differ, in both cases, the C to U change plays a key role in A to I editing. Due to an unusual abundance of A34-containing tRNAs, our results also suggest that the unedited and edited tRNAs are functional, each dedicated to decoding a specific threonine codon. C to U editing of cytoplasmic tRNA expands the editing repertoire in eukaryotic cells, and when coupled to A to I changes, leads to an interrelation between editing sites

Multi-Substrate Specificity and the Evolutionary Basis for Interdependence in tRNA Editing and Methylation Enzymes

Among tRNA modification enzymes there is a correlation between specificity for multiple tRNA substrates and heteromultimerization. In general, enzymes that modify a conserved residue in different tRNA sequences adopt a heterodimeric structure. Presumably, such changes in the oligomeric state of enzymes, to gain multi-substrate recognition, are driven by the need to accommodate and catalyze a particular reaction in different substrates while maintaining high specificity. This review focuses on two classes of enzymes where the case for multimerization as a way to diversify molecular recognition can be made. We will highlight several new themes with tRNA methyltransferases and will also discuss recent findings with tRNA editing deaminases. These topics will be discussed in the context of several mechanisms by which heterodimerization may have been achieved during evolution and how these mechanisms might impact modifications in different systems

Un taller en herramientas web para la sistematización de datos. Una experiencia de actualización de conocimientos

Se expone una experiencia de actualización de conocimientos en herramientas para la generación de aplicaciones web, desarrollada en el ámbito universitario, orientada a fomentar el desarrollo personal y profesional de los participantes. En el trabajo se explicita la estrategia didáctica aplicada, los resultados obtenidos siendo sus destinatarios estudiantes avanzados y principiantes con diversos conocimientos respecto a los temas abordados.

The Reverse Transcription Signature of N-\u3csub\u3e1\u3c/sub\u3e-Methyladenosine in RNA-Seq is Sequence Dependent

The combination of Reverse Transcription (RT) and high-throughput sequencing has emerged as a powerful combination to detect modified nucleotides in RNA via analysis of either abortive RT-products or of the incorporation of mismatched dNTPs into cDNA. Here we simultaneously analyze both parameters in detail with respect to the occurrence of N-1-methyladenosine (m1A) in the template RNA. This naturally occurring modification is associated with structural effects, but it is also known as a mediator of antibiotic resistance in ribosomal RNA. In structural probing experiments with dimethylsulfate, m1A is routinely detected by RT-arrest. A specifically developed RNA-Seq protocol was tailored to the simultaneous analysis of RT-arrest and misincorporation patterns. By application to a variety of native and synthetic RNA preparations, we found a characteristic signature of m1A, which, in addition to an arrest rate, features misincorporation as a significant component. Detailed analysis suggests that the signature depends on RNA structure and on the nature of the nucleotide 3’ of m1A in the template RNA, meaning it is sequence dependent. The RT-signature ofm1Awas used for inspection and confirmation of suspected modification sites and resulted in the identification of hitherto unknown m1A residues in trypanosomal tRNA

C to U editing at position 32 of the anticodon loop precedes tRNA 5′ leader removal in trypanosomatids

In all organisms, precursor tRNAs are processed into mature functional units by post-transcriptional changes. These involve 5′ and 3′ end trimming as well as the addition of a significant number of chemical modifications, including RNA editing. The only known example of non-organellar C to U editing of tRNAs occurs in trypanosomatids. In this system, editing at position 32 of the anticodon loop of tRNAThr(AGU) stimulates, but is not required for, the subsequent formation of inosine at position 34. In the present work, we expand the number of C to U edited tRNAs to include all the threonyl tRNA isoacceptors. Notably, the absence of a naturally encoded adenosine, at position 34, in two of these isoacceptors demonstrates that A to I is not required for C to U editing. We also show that C to U editing is a nuclear event while A to I is cytoplasmic, where C to U editing at position 32 occurs in the precursor tRNA prior to 5′ leader removal. Our data supports the view that C to U editing is more widespread than previously thought and is part of a stepwise process in the maturation of tRNAs in these organisms

Comunicación y accesibilidad en sitios web municipales de la Región del Nordeste Argentino, su evaluación mediante validadores automáticos

Recientemente se promulgó en la Argentina la ley de accesibilidad. Con esta decisión gubernamental el estudio de información accesible representa significa un nuevo valor en la sociedad del conocimiento. Este trabajo forma parte de una investigación centrada en la evaluación de la accesibilidad de sitios web municipales de la región NEA de la Argentina: Corrientes, Chaco, Misiones y Formosa. Se estudió una metodología y se adaptó para su aplicación en la medición de los sitios seleccionados. El estudio sobre sitios municipales es el  marco de aplicación y trasferencia para  introducir en la región un tema que resulta de gran actualidad internacional  en el ámbito de la disciplina Informática como es la accesibilidad web