Ribonuclease H, an unexploited target for antiviral intervention against HIV and hepatitis B virus

Ribonucleases H (RNases H) are endonucleolytic enzymes, evolutionarily related to retroviral integrases, DNA transposases, resolvases and numerous nucleases. RNases H cleave RNA in RNA/DNA hybrids and their activity plays an important role in the replication of prokaryotic and eukaryotic genomes, as well as in the replication of reverse-transcribing viruses. During reverse transcription, the RNase H activity of human immunodeficiency virus (HIV) and hepatitis B virus (HBV) degrades the viral genomic RNA to facilitate the synthesis of viral double-stranded DNA. HIV and HBV reverse transcriptases contain DNA polymerase and RNase H domains that act in a coordinated manner to produce double-stranded viral DNA. Although RNase H inhibitors have not been developed into licensed drugs, recent progress has led to the identification of a number of small molecules with inhibitory activity at low micromolar or even nanomolar concentrations. These compounds can be classified into metal-chelating active site inhibitors and allosteric inhibitors. Among them, α-hydroxytropolones, N-hydroxyixoquinolinediones and N-hydroxypyridinediones represent chemotypes active against both HIV and HBV RNases H. In this review we summarize recent developments in the field including the identification of novel RNase H inhibitors, compounds with dual activity, broad specificity and efforts to decrease their toxicity

Unionism 4.0? The organization of platform workers in Argentina

Este artículo presenta los resultados de una investigación llevada a cabo en Argentina durante los años 2018 y 2019. El estudio se inscribe en los debates sobre las posibilidades de organización colectiva de los trabajadores de empresas de plataformas. Se analiza en particular las características que tiene el proceso de trabajo en las plataformas de delivery que desarrollan actividades en la Ciudad de Buenos Aires: Rappi, Glovo y PedidosYa.Además, se describen las particularidades que tiene el modelo sindical en Argentina y en función de distintas dimensiones de análisis, se construyen de manera esquemática dos tradiciones que han caracterizado al sindicalismo argentino.Recuperando esas dos tradiciones sindicales se analizan las acciones desarrolladas por los dos sindicatos que representan los intereses de los riders: la ASIMM, un sindicato preexistente que representa a los trabajadores de mensajería, y la APP, un sindicato creado para defender a los trabajadores de plataformas específicamente.This article presents the results of a study conducted in Argentina during 2018 and 2019. The study engages in the debates around the possibilities for collective organization of platform workers. In particular it analyzes the characteristics of the labour process on delivery platforms in the city of Buenos Aires: Rappi, Glovo, and PedidosYa. In addition, is describes the specific features of the Argentinian union model and on the basis of different dimensions of analysis, two traditions that have characterized Argentinian unionism are constructed schematically. In the light of these union traditions, we analyze the actions developed by the two unions representing the interests of riders: ASIMM, the pre-existing union that represents couriers, and APP, a union set up to specifically defend platform workers.Fil: Arias, Cora Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Innovación de los Trabajadores. Universidad Metropolitana para la Educación y el Trabajo. Centro de Innovación de los Trabajadores; ArgentinaFil: Diana Menendez, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Innovación de los Trabajadores. Universidad Metropolitana para la Educación y el Trabajo. Centro de Innovación de los Trabajadores; ArgentinaFil: Haidar, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Innovación de los Trabajadores. Universidad Metropolitana para la Educación y el Trabajo. Centro de Innovación de los Trabajadores; Argentin

The collective organization beats the algorithm(?): delivery platforms and the organization of delivery workers in Argentina

Indagamos cómo la gestión algorítmica y la organización del trabajo en las plataformas crean condiciones que habilitan u obstruyen la organización colectiva de los trabajadores, y cómo estos trabajadores utilizan estas mismas características para desarrollar estrategias colectivas de resistencia. El abordaje es cualitativo, basado en entrevistas en profundidad realizadas a activistas y repartidores de las tres principales empresas de reparto en la Ciudad Autónoma de Buenos Aires. Concluimos que las características de la gestión algorítmica generaron sentimientos de insatisfacción entre los repartidores quienes, alentados por los activistas, ayudaron a desarrollar recursos de poder asociativo, articulados con el poder de negociación en el lugar de trabajo y el poder discursivo para resistir las prácticas de explotación de las empresas.We discuss how algorithmic management and work organization on platforms create conditions that enable or obstruct the collective organization of workers, and h ow these workers use these same characteristics to develop collective strategies of resistance. This is a qualitative approach, based o n in-depth interviews with activists and delivery people from the three main delivery companies in Buenos Aires City. In the conclusions we show that the characteristics of algorithmic management generated feelings of dissatisfaction among the riders who, encouraged by the activists, helped to develop associative power resources, articulated with the bargaining power in the workplace and the discursive power to resist business operating practices.Fil: Haidar, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Innovación de los Trabajadores. Universidad Metropolitana para la Educación y el Trabajo. Centro de Innovación de los Trabajadores; ArgentinaFil: Diana Menendez, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Innovación de los Trabajadores. Universidad Metropolitana para la Educación y el Trabajo. Centro de Innovación de los Trabajadores; Argentina. Universidad Nacional de San Martín. Instituto de Altos Estudios Sociales; ArgentinaFil: Arias, Cora Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Innovación de los Trabajadores. Universidad Metropolitana para la Educación y el Trabajo. Centro de Innovación de los Trabajadores; Argentin

Reverse transcriptases can clamp together nucleic acids strands with two complementary bases at their 3′-termini for initiating DNA synthesis

We present evidence that the reverse transcriptase (RT) of human immunodeficiency virus type-1 stabilizes in vitro very short (2-nt) duplexes of 3′-overhangs of the primer strand that are annealed to complementary dinucleotides tails of DNA or RNA template strands, provided that these sequences contain at least one C or G. This RT-induced strand ‘clamping’ activity promotes RT-directed DNA synthesis. This function is achieved only when the functional template strand is adjacent to a second DNA or RNA segment, annealed upstream to most of the primer (without gaps). The combined clamp/polymerase activity is typical to RTs, as it was found in different RTs from diverse retroviral groups, whereas cellular DNA-polymerases (devoid of 3′→5′ exonucleolytic activity) showed no clamp activity. The clamp-associated DNA-binding activity is markedly stabilized by dGTP, even when dGTP is not incorporated into the nascent DNA strand. The hereby-described function can help RTs in bridging over nicks in the copied RNA or DNA templates, encountered during reverse transcription. Moreover, the template-independent blunt-end synthesis of RTs can allow strand transfers onto compatible acceptor strands while synthesizing DNA. These RT properties can shed light on potentially-new roles of RTs in the reverse-transcription process and define new targets for anti-retroviral drugs

Comparative Studies on Retroviral Proteases: Substrate Specificity

Exogenous retroviruses are subclassified into seven genera and include viruses that cause diseases in humans. The viral Gag and Gag-Pro-Pol polyproteins are processed by the retroviral protease in the last stage of replication and inhibitors of the HIV-1 protease are widely used in AIDS therapy. Resistant mutations occur in response to the drug therapy introducing residues that are frequently found in the equivalent position of other retroviral proteases. Therefore, besides helping to understand the general and specific features of these enzymes, comparative studies of retroviral proteases may help to understand the mutational capacity of the HIV-1 protease

Clinicopathological characteristics of infiltrating lobular breast carcinoma in elderly women: Preliminary results

This study was conducted to investigate the clinicopathological parameters in elderly women (aged >70 years) with infiltrating lobular carcinoma (ILC) of the breast and compare the results with those obtained from younger patients (aged 55-70 years). The study sample included a total of 46 women with ILCs, 10 aged >70 and 36 aged 55-70 years. The parameters analysed were tumor size, histological grade (HG), axillary lymph node involvement, distant metastasis and immunohistochemical expression of estrogen, progesterone and androgen receptors, Ki67, p53 and B cell lymphoma 2. Compared to women aged 55-70 years, ILCs in women aged >70 years were commonly of larger size (P=0.068) and were more frequently HG3 (P=0.024). There were no statistically significant differences in the other parameters analysed. Furthermore, we were unable to determine differences in cancer recurrence and mortality in the two patient subgroups during our follow-up. In conclusion, our preliminary results, based on the limited number of cases included in this study, indicate that i) ILCs in women aged >70 years tended to be larger compared to those in women aged 55-70 years and were more frequently of grade 3; and ii) there were no significant differences in terms of recurrence and mortality between the two patient subgroups during our follow-up

Effect of the human immunodeficiency virus type 1 reverse transcriptase polymorphism Leu-214 on replication capacity and drug susceptibility

A negative association between polymorphism Leu-214 and type-1 thymidine analogue mutations (TAM1) and a positive association with a clinically favorable virological response to thymidine analogue-based combination antiretroviral therapy have been described. In this study, the impact of Leu-214 on replication capacity and resistance to zidovudine (ZDV) of viruses containing TAM1 or TAM2 was determined. Leu-214 decreased the growth rate of viruses bearing Tyr-215, as well as their resistance to ZDV. This observation was confirmed by structural and molecular modeling data, suggesting a regulatory role for Leu-214 in the emergence and phenotypic resistance of TAM1

Las plataformas de reparto en Argentina: Entre el cambio de gobierno y la pandemia

En este informe se presentan los resultados de una investigación llevada adelante por el equipo de plataformas del CITRA. El objetivo del estudio es describir y analizar las transformaciones producidas en el sector del delivery de plataformas en general, y en las relaciones laborales en particular, durante la pandemia en Argentina. Las empresas de plataforma de reparto se instalaron en el país a comienzos de 2018 en un contexto propicio para su despliegue y consolidación. El cambio de signo político en el gobierno a fines de 2019 y, fundamentalmente, el advenimiento de la pandemia y el confinamiento en marzo de 2020 constituyen puntos de inflexión que modifican el desarrollo de estas empresas. En base a datos cuantitativos y cualitativos recolectados durante 2020 y 2021, se analiza el impacto de esos puntos de inflexión en diferentes aspectos de la configuración del modelo de negocios y de la relación capital-trabajo en las plataformas: la presencia y desarrollo de las plataformas en el mercado argentino, sus vínculos con los/as proveedores/as o comercios “aliados” o “partners”, los perfiles sociodemográficos de las y los trabajadores de reparto y las dinámicas de trabajo durante la pandemia, las formas de organización y protesta de las/os trabajadoras/es, y las propuestas de regulación laboral a nivel nacional y subnacional. Los principales resultados de la investigación indican que las plataformas de reparto se convirtieron en una actividad refugio en un contexto de creciente desocupación, pero que ese trabajo es informal y precario. Las condiciones abusivas de estas empresas no se dirigen únicamente hacia el colectivo laboral, sino también hacia los locales gastronómicos que, durante el aislamiento, se vieron forzados a utilizarlas para subsistir. En consecuencia, se requiere la imperiosa intervención de las autoridades gubernamentales para contener y regular a las plataformas. Se trata de un fenómeno mundial en expansión que va construyendo nuevos mercados y hábitos de consumo. Para poder mitigar los daños generados por el avance desmesurado de estas empresas, se torna indispensable articular mecanismos de control a nivel internacional y, desde la fuerza laboral, coordinar acciones internacionales que visibilicen y denuncien los excesos cometidos.This report presents the findings of research carried out by the platform work study group of CITRA. The objective of the study is to describe and analyze the transformations produced in food delivery platforms in general, and in labour relations in particular, during the pandemic in Argentina. Delivery platform companies arrived to the country at the beginning of 2018 in a favourable context for their development and consolidation. The change of government at the end of 2019 and, fundamentally, the emergence of the pandemic and the lockdown in March 2020, are turning points that modify the development of these companies. Based on quantitative and qualitative data collected during 2020 and 2021, the impact of these turning points on different aspects of the configuration of the business model and the capital-labour relations in the platforms is analyzed: the presence and development of the platforms in the Argentine market, their links with suppliers or “ally” or “partner” businesses, the sociodemographic profiles of the delivery workers and the work dynamics during the pandemic, the forms of organization and protest of the workers, and the proposals for labour regulation at the national and subnational levels. The main research findings indicate that the delivery platforms became a refuge activity in a context of growing unemployment, but that this work is informal and precarious. The abusive conditions of these companies do not only concern the workers, but also the food businesses that, during the lockdown, were forced to use them to survive. Consequently, the intervention of government authorities is required to contain and regulate the platforms. They constitute an expanding global phenomenon, which is constructing new markets and consumption habits. In order to mitigate the damages generated by the uncontrolled advance of these companies, it is essential to articulate control mechanisms at international level and, from the side of the workforce, to coordinate international actions that make visible and denounce the excesses of the platform companies.Fil: Diana Menendez, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Innovación de los Trabajadores. Universidad Metropolitana para la Educación y el Trabajo. Centro de Innovación de los Trabajadores; ArgentinaFil: Bordarampé, Gastón José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Innovación de los Trabajadores. Universidad Metropolitana para la Educación y el Trabajo. Centro de Innovación de los Trabajadores; ArgentinaFil: Pérez, Milagros Ailén. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Innovación de los Trabajadores. Universidad Metropolitana para la Educación y el Trabajo. Centro de Innovación de los Trabajadores; ArgentinaFil: Arias, Cora Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Innovación de los Trabajadores. Universidad Metropolitana para la Educación y el Trabajo. Centro de Innovación de los Trabajadores; Argentin

The chemical stability of abasic RNA compared to abasic DNA

We describe the synthesis of an abasic RNA phosphoramidite carrying a photocleavable 1-(2-nitrophenyl)ethyl (NPE) group at the anomeric center and a triisopropylsilyloxymethyl (TOM) group as 2′-O-protecting group together with the analogous DNA and the 2′-OMe RNA abasic building blocks. These units were incorporated into RNA-, 2′-OMe-RNA- and DNA for the purpose of studying their chemical stabilities towards backbone cleavage in a comparative way. Stability measurements were performed under basic conditions (0.1 M NaOH) and in the presence of aniline (pH 4.6) at 37°C. The kinetics and mechanisms of strand cleavage were followed by High pressure liquid chromotography and ESI-MS. Under basic conditions, strand cleavage at abasic RNA sites can occur via β,δ-elimination and 2′,3′-cyclophosphate formation. We found that β,δ-elimination was 154-fold slower compared to the same mechanism in abasic DNA. Overall strand cleavage of abasic RNA (including cyclophosphate formation) was still 16.8 times slower compared to abasic DNA. In the presence of aniline at pH 4.6, where only β,δ-elimination contributes to strand cleavage, a 15-fold reduced cleavage rate at the RNA abasic site was observed. Thus abasic RNA is significantly more stable than abasic DNA. The higher stability of abasic RNA is discussed in the context of its potential biological role

Trans-lesion synthesis and RNaseH activity by reverse transcriptases on a true abasic RNA template

While much is known about abasic DNA, the biological impact of abasic RNA is largely unexplored. To test the mutagenic potential of this RNA lesion in the context of retroviruses, we synthesized a 31-mer oligoribonucleotide containing an abasic (rAS) site and used it as a template for studying DNA primer extension by HIV-1, avian myeloblastosis virus (AMV) and moloney murine leukemia virus (MMLV) reversed transcriptases (RT). We found that trans-lesion synthesis readily takes place with HIV-1 RT and to a lesser extent with AMV RT while MMLV RT aborts DNA synthesis. The preference of dNTP incorporation follows the order A∼G > C∼T and thus obeys to the ‘A-rule’. In the case of HIV-1 RT, we measured the kinetic data of dNTP incorporation and compared it to abasic DNA. We found that A-incorporation is only 2-fold slower relative to a matched (undamaged) RNA template while it is 7-fold slower in the case of DNA. Furthermore, there is less discrimination in incorporation between the four dNTPs in the case of abasic RNA compared to abasic DNA. These experiments clearly point to a higher promiscuity of lesion bypass on abasic RNA. Given their known higher chemical stability, such rAS sites can clearly contribute to (retro)viral evolution