142 research outputs found
A Dynamic Linkage between Financial Development, Energy Consumption and Economic Growth: Evidence from an Asymmetric and Nonlinear ARDL Model
Developing countries, including Pakistan, need a considerable effort to withstand economic growth; however, these countries have to cope with greenhouse gases emission and other environmental concerns. Financial advancement gives rise to modern, sometimes even innovative and energy-efficient technologies and, thus, contributes to a decline in energy usage among market entities: organizations and households. The current study explores the nonlinear asymmetric relationship between economic growth (Y) and the selected exogenous variables in Pakistan by incorporating time series data spanning from 1971 to 2016. Economic growth was considered as a target variable, while energy consumption (EC), electric power consumption (EPC), financial development (FD), and energy imports (EM) were considered independent variables. To investigate cointegration among the given variables, a nonlinear ARDL bound testing approach was employed. BDS independence test was used to check the nonlinearity, and a structural break unit root test was used for testing data stationarity. The findings confirm the presence of co-integration in the selected variables. A symmetric unidirectional significant causality exists running from EPC to Y, while a bidirectional symmetric causality was found between FD and Y. In contrast, any negative shocks in EPC, FD, and EM were found to have a positive asymmetric effect on Y. Meanwhile, a neutral effect was found between EC and Y. The outcomes of this study can provide guidelines for future re-searchers and policymakers. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Kinetic CRAC uncovers a role for Nab3 in determining gene expression profiles during stress
RNA-binding proteins play a key role in shaping gene expression profiles during stress, however, little is known about the dynamic nature of these interactions and how this influences the kinetics of gene expression. To address this, we developed kinetic cross-linking and analysis of cDNAs (\u3c7CRAC), an ultraviolet cross-linking method that enabled us to quantitatively measure the dynamics of protein\u2013RNA interactions in vivo on a minute time-scale. Here, using \u3c7CRAC we measure the global RNA-binding dynamics of the yeast transcription termination factor Nab3 in response to glucose starvation. These measurements reveal rapid changes in protein\u2013RNA interactions within 1\u2009min following stress imposition. Changes in Nab3 binding are largely independent of alterations in transcription rate during the early stages of stress response, indicating orthogonal transcriptional control mechanisms. We also uncover a function for Nab3 in dampening expression of stress-responsive genes. \u3c7CRAC has the potential to greatly enhance our understanding of in vivo dynamics of protein\u2013RNA interactions
Mutations of RNA polymerase II activate key genes of the nucleoside triphosphate biosynthetic pathways
The yeast URA2 gene, encoding the rate-limiting enzyme of UTP biosynthesis, is transcriptionally activated by UTP shortage. In contrast to other genes of the UTP pathway, this activation is not governed by the Ppr1 activator. Moreover, it is not due to an increased recruitment of RNA polymerase II at the URA2 promoter, but to its much more effective progression beyond the URA2 mRNA start site(s). Regulatory mutants constitutively expressing URA2 resulted from cis-acting deletions upstream of the transcription initiator region, or from amino-acid replacements altering the RNA polymerase II Switch 1 loop domain, such as rpb1-L1397S. These two mutation classes allowed RNA polymerase to progress downstream of the URA2 mRNA start site(s). rpb1-L1397S had similar effects on IMD2 (IMP dehydrogenase) and URA8 (CTP synthase), and thus specifically activated the rate-limiting steps of UTP, GTP and CTP biosynthesis. These data suggest that the Switch 1 loop of RNA polymerase II, located at the downstream end of the transcription bubble, may operate as a specific sensor of the nucleoside triphosphates available for transcription
Transcriptome-Wide Binding Sites for Components of the Saccharomyces cerevisiae Non-Poly(A) Termination Pathway: Nrd1, Nab3, and Sen1
RNA polymerase II synthesizes a diverse set of transcripts including both protein-coding and non-coding RNAs. One major difference between these two classes of transcripts is the mechanism of termination. Messenger RNA transcripts terminate downstream of the coding region in a process that is coupled to cleavage and polyadenylation reactions. Non-coding transcripts like Saccharomyces cerevisiae snoRNAs terminate in a process that requires the RNA–binding proteins Nrd1, Nab3, and Sen1. We report here the transcriptome-wide distribution of these termination factors. These data sets derived from in vivo protein–RNA cross-linking provide high-resolution definition of non-poly(A) terminators, identify novel genes regulated by attenuation of nascent transcripts close to the promoter, and demonstrate the widespread occurrence of Nrd1-bound 3′ antisense transcripts on genes that are poorly expressed. In addition, we show that Sen1 does not cross-link efficiently to many expected non-coding RNAs but does cross-link to the 3′ end of most pre–mRNA transcripts, suggesting an extensive role in mRNA 3′ end formation and/or termination
INVESTIGATION OF IRON CONTAINING ATMOSPHERIC AEROSOLS
En appliquant la technique de l'effet Mössbauer on a étudié les variations saisonnières des concentrations du fer dans l'air atmosphérique. Les mesures sont faites dans le domaine de températures allant de 300 K à 75 K pour les échantillons préparés des filtres. La concentration du fer dans l'air a été calculée à partir des spectres Mössbauer par la méthode du champ. L'analyse des spectres Mössbauer montre que le fer est lié en Fe2O3 sous forme de particules ultrafines en état superparamagnétique. Les mesures ont permis d'évaluer les dimensions des particules d'aérosol contenant le fer. On a discuté la relation des variations saisonnières des concentrations du fer avec l'activité des météors. On a essayé de trouver la relation entre la pollution de l'air et la concentration du fer atmosphérique.The seasonal variations of iron concentration in atmospheric air were studied using the Mössbauer technique. Mössbauer measurements were performed in the temperature range from 300 K to 75 K for samples prepared using filters through which a given volume of air was pumped. The concentration of iron in air was calculated by the area method from the experimental spectra obtained. From the shapes of the Mössbauer spectra it was inferred that iron appears as Fe2O3 in the form of ultrafine particles in the superparamagnetic state. The temperature measurements made it possible to estimate the size of iron containing aerosol particles. Correlation of the seasonal variations of iron concentration with meteroite activity was discussed. Attempts were made to find a relation between the air pollution and the concentration of iron in atmospheric air
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