Mechanism of Riboswitch Regulatory Domains and Application for Developing Novel Biosensors

Riboswitches are structural elements of gene control located in the 5’- untranslated region of some mRNAs capable of regulating the expression of important genes. The mode of regulation occurs by binding a cellular metabolite if its concentration excess a threshold and controlling genes involved in the biogenesis or transport of this ligand. A common riboswitch is composed of two functionally distinct units: i) the aptamer domain, which recognizes and binds the cellular metabolite and ii) an expression platform responsible for interaction with the cellular machinery and control of gene production. The aptamer domain of riboswitches confers high degree of affinity and specificity towards the correct ligand. This binding event rearranges the secondary structure of the expression platform, which in turn allows regulation of gene expression. Riboswitch genetic control is observed in the three domains of life. However, it is most important in bacteria. Previously, the characterization of riboswitches has focused on the biophysical study of different aptamer domains and the changes that occur when the ligand binds the RNA. These studies have revealed the intricate recognition of essentially every functional group of a diverse set of cellular metabolites by RNAs. However, the signal transduction from the aptamer domain to the expression platform remains uncharacterized. Most importantly, the secondary structural switch that an expression platform undergoes has been reduced to a simple variation of secondary interactions. In this dissertation, I have functionally characterized, both in vitro and in vivo, two different riboswitches in their entirety, demonstrating novel findings about the regulatory response of these riboregulators. The results show that small secondary structures formed within the expression platform are important for gene control and that the ability of the switching mechanism is innate within this domain (independent of ligand presence). The application of these learned principles of riboswitch regulation for the development of novel RNA-based biosensors has also been accomplished. To establish engineering strategies capable of developing general, reliable, and modular RNA devices, I mixed and matched natural and SELEX-derived (systematic evolution of ligands by exponential enrichment) aptamers with a variation of natural expression platforms. These engineered riboswitches are functional in vitro and in E. coli, and present a new avenue to control cellular regulation for different applications including synthetic biology

Coastal high-frequency radars in the Mediterranean ??? Part 2: Applications in support of science priorities and societal needs

International audienceThe Mediterranean Sea is a prominent climate-change hot spot, with many socioeconomically vital coastal areas being the most vulnerable targets for maritime safety, diverse met-ocean hazards and marine pollution. Providing an unprecedented spatial and temporal resolution at wide coastal areas, high-frequency radars (HFRs) have been steadily gaining recognition as an effective land-based remote sensing technology for continuous monitoring of the surface circulation, increasingly waves and occasionally winds. HFR measurements have boosted the thorough scientific knowledge of coastal processes, also fostering a broad range of applications, which has promoted their integration in coastal ocean observing systems worldwide, with more than half of the European sites located in the Mediterranean coastal areas. In this work, we present a review of existing HFR data multidisciplinary science-based applications in the Mediterranean Sea, primarily focused on meeting end-user and science-driven requirements, addressing regional challenges in three main topics: (i) maritime safety, (ii) extreme hazards and (iii) environmental transport process. Additionally, the HFR observing and monitoring regional capabilities in the Mediterranean coastal areas required to underpin the underlying science and the further development of applications are also analyzed. The outcome of this assessment has allowed us to provide a set of recommendations for future improvement prospects to maximize the contribution to extending science-based HFR products into societally relevant downstream services to support blue growth in the Mediterranean coastal areas, helping to meet the UN's Decade of Ocean Science for Sustainable Development and the EU's Green Deal goals

Coastal high-frequency radars in the Mediterranean ??? Part 1: Status of operations and a framework for future development

Due to the semi-enclosed nature of the Mediterranean Sea, natural disasters and anthropogenic activities impose stronger pressures on its coastal ecosystems than in any other sea of the world.With the aim of responding adequately to science priorities and societal challenges, littoral waters must be effectively monitored with high-frequency radar (HFR) systems. This land-based remote sensing technology can provide, in near-real time, fine-resolution maps of the surface circulation over broad coastal areas, along with reliable directional wave and wind information. The main goal of this work is to showcase the current status of the Mediterranean HFR network and the future roadmap for orchestrated actions. Ongoing collaborative efforts and recent progress of this regional alliance are not only described but also connected with other European initiatives and global frameworks, highlighting the advantages of this cost-effective instrument for the multi-parameter monitoring of the sea state. Coordinated endeavors between HFR operators from different multi-disciplinary institutions are mandatory to reach a mature stage at both national and regional levels, striving to do the following: (i) harmonize deployment and maintenance practices; (ii) standardize data, metadata, and quality control procedures; (iii) centralize data management, visualization, and access platforms; and (iv) develop practical applications of societal benefit that can be used for strategic planning and informed decision-making in the Mediterranean marine environment. Such fit-for-purpose applications can serve for search and rescue operations, safe vessel navigation, tracking of marine pollutants, the monitoring of extreme events, the investigation of transport processes, and the connectivity between offshore waters and coastal ecosystems. Finally, future prospects within the Mediterranean framework are discussed along with a wealth of socioeconomic, technical, and scientific challenges to be faced during the implementatio

Hepatitis B Virus Capsid Assembly Is Enhanced by Naturally Occurring Mutation F97L

In chronic hepatitis B virus (HBV) infections, one of the most common mutations to the virus occurs at amino acid 97 of the core protein, where leucine replaces either phenylalanine or isoleucine, depending on strain. This mutation correlates with changes in viral nucleic acid metabolism and/or secretion. We hypothesize that this phenotype is due in part to altered core assembly, a process required for DNA synthesis. We examined in vitro assembly of empty HBV capsids from wild-type and F97L core protein assembly domains. The mutation enhanced both the rate and extent of assembly relative to those for the wild-type protein. The difference between the two proteins was most obvious in the temperature dependence of assembly, which was dramatically stronger for the mutant protein, indicating a much more positive enthalpy. Since the structures of the mutant and wild-type capsids are essentially the same and the mutation is not involved in the contact between dimers, we suggest that the F97L mutation affects the dynamic behavior of dimer and capsid

ATITUDES COM REFERÊNCIA ÀS LÍNGUAS CASTELHANO E GUARANI

Abstract: This paper reports part of a research made in a school in the city of Presidente Franco (Alto Paraguay), with seven teachers who use two languages daily – Spanish and Guarani. The goal of the work was analyzing interaction situations in which the speakers - focus of the study - use different linguistic codes, taking turns with them during speaking events. In order to develop the analyses, questions were made to check the speakers attitudes regarding the use of their languages. The theory that has based the study comes from contributions of Grosjean (1982), Erikson (1989), Pereira (1999), André (1995), among others. Results have shown that these teachers use their languages in different contexts and diglossic situations which are inherent to the community they live. It was also noticed that in spite of Guarani language is part of their linguistic common use, situations of its use usually depend on the context and the subject´s hegemonic view toward his own language. Keywords: bilingualism, linguistic attitudes, Spanish/Guarani.Resumo: Este artigo relata parte de uma pesquisa realizada em uma escola da cidade de Presidente Franco (Alto Paraná, Paraguai), com sete docentes que são usuários de duas línguas, a saber, espanhol e guarani. Neste trabalho, buscou-se analisar as situações interacionais em que os falantes sujeitos desta pesquisa, utilizam os códigos linguísticos, alternando-os em eventos de fala. Para alcançar esse objetivo, foram elaboradas questões para verificar as atitudes com relação ao uso dessas línguas. O arcabouço teórico que orientou o nosso trabalho advem das contribuições de Grosjean (1982), Erikson (1989), Pereira (1999), André (1995), entre outros. Os resultados mostraram que esses docentes fazem uso de suas línguas em diferentes contextos e situações diglóssicas inerentes àquela comunidade. Percebe-se ainda que, embora a língua guarani faça parte de seu repertório linguístico, as situações de seu uso dependerão do contexto e da visão hegemônica do sujeito com respeito a sua língua. Palavras-chave: Bilinguismo, atitudes linguísticas, castelhano/guarani

Atitudes com referência às línguas Castelhano e Guarani = Attitudes on the Spanish and Guarani languages

Este artigo relata parte de uma pesquisa realizada em uma escola da cidade de Presidente Franco (Alto Paraná, Paraguai), com sete docentes que são usuários de duas línguas, a saber, espanhol e guarani. Neste trabalho, buscou-se analisar as situações interacionais em que os falantes sujeitos desta pesquisa utilizam os códigos linguísticos, alternando-os em eventos de fala. Para alcançar esse objetivo, foram elaboradas questões para verificar as atitudes com relação ao uso dessas línguas. O arcabouço teórico que orientou o nosso trabalho advem das contribuições de Grosjean (1982), Erickson (1989), Pereira (1999), André (1995), entre outros. Os resultados indicam que esses docentes fazem uso de suas línguas em diferentes contextos e situações diglóssicas inerentes àquela comunidade. Percebe-se ainda que, embora a língua guarani faça parte de seu repertório linguístico, as situações de seu uso dependerão do contexto e da visão hegemônica do sujeito com referência a sua língua.This paper reports part of a research performed in a school in the city of Presidente Franco (Alto Paraná, Paraguay), with seven teachers who use two languages daily – Spanish and Guarani. Thegoal of the work was to analyze interactions in which the speakers - focus of the study - use and alternate different linguistic codes during speaking events. In order to develop the analyses, questions were elaborated to check the speakers’ attitudes regarding the use ofthose languages. This study was based on the contributions of Grosjean (1982), Erickson (1989), Pereira (1999), André (1995), among others. Results have shown that these teachers use their languages in different contexts and diglossic situations, which are inherent to their community. Also although the Guarani language is part of their linguistic common use, situations on its use usually depend on the context and the subject´s hegemonic view concerning the own language