Factors directing the RNA-dependent RNA polymerase jump during discontinuous transcription in coronaviruses

It has been 23 years since it was learned that coronavirus subgenomic messenger RNAs are unusual among virus messenger RNAs in that they are 5\u27 and 3\u27 co-terminal with the plus-strand RNA viral genome. Although it is generally agreed that the co-terminal structure is the result of a discontinuous transcription process whereby the RNA-dependent RNA polymerase (RdRP) jumps in a high-frequency (sequence) similarity-assisted manner (resembling copy-choice recombination) from a donor to an acceptor RNA strand, it is not known what mechanisms direct the Rd.Rp to jump. Here, with the use of a bovine coronavirus minireplicon (a defective interfering RNA), it is documented that (1) group 2 corona virus RNA replication signals recognized by the viral RdRps (among six group 2 coronaviruses studied) are common whereas the transcription signals directing discontinuous transcription are not, (2) a 22-nt region of sequence identity is sufficient to direct the RdRp to jump from the positive-strand minireplicon donor to the positive-strand virus genome acceptor as long as it occurs within the precisely restricted window of nts 33 to 97 within the 5\u27-proximal region of the 31032-nt genome, (3) a 22-nt region of sequence identity is sufficient to direct the RdRp to jump from the positive-strand minireplicon donor to the virus negative-strand antigenome as long as it occurs within the precisely restricted window of nts 35 to 123 from the 3\u27 end of the antigenome, and (4) the 22- nt region of sequence identity can dire.ct the RdRp jump to yield a subgenomic messenger RNA with a leader as short as 33 nt, but no shorter. These results show that specific RNA structural elements direct the RdRp jump during the required intermolecular recombination events (i.e. discontinuous transcription) in the process of coronavirus replication. Rational drug designs for interrupting these elements may lead to therapeutic molecules for treating coronavirus infection, including infection by the SARS coronavirus which to date appears to be a group 2 member

Rotating Black Holes and Coriolis Effect

In this work, we consider the fluid/gravity correspondence for general rotating black holes. By using the Petrov-like boundary condition in near horizon limit, we study the correspondence between gravitational perturbation and fluid equation. We find that the dual fluid equation for rotating black holes contains a Coriolis force term, which is closely related to the angular velocity of the black hole horizon. This can be seen as a dual effect for the frame-dragging effect of rotating black hole under the holographic picture.Comment: 5 page

Antidumping Petition: To File or Not To File

Given the “normal value†of a product as common knowledge in an import-competing market, the profitability of a home firm in filing an antidumping (AD) petition against its foreign rival is shown to depend on the marginal cost differential between the home and foreign firms. When the marginal cost differential is “significantly large,†the home firm's ability to put the foreign firm at the risk of an AD violation is limited. But when the marginal cost differential is “significantly small,†the home firm is able to increase its output and lower the price of the product below its normal value, putting the foreign firm in the situation of an illegal dumping. One interesting implication is that, relative to the case without an AD law, the home firm has a stronger incentive to undertake cost-reducing activities (e.g., R&D investment or the adoption of a more efficient technology) under the law.antidumping laws, antidumping duties, dumping margins

Identification of cis-acting elements on positive-strand subgenomic mRNA required for the synthesis of negative-strand counterpart in bovine coronavirus

It has been demonstrated that, in addition to genomic RNA, sgmRNA is able to serve as a template for the synthesis of the negative-strand [(-)-strand] complement. However, the cis-acting elements on the positive-strand [(+)-strand] sgmRNA required for (-)-strand sgmRNA synthesis have not yet been systematically identified. In this study, we employed real-time quantitative reverse transcription polymerase chain reaction to analyze the cis-acting elements on bovine coronavirus (BCoV) sgmRNA 7 required for the synthesis of its (-)-strand counterpart by deletion mutagenesis. The major findings are as follows. (1) Deletion of the 5'-terminal leader sequence on sgmRNA 7 decreased the synthesis of the (-)-strand sgmRNA complement. (2) Deletions of the 3' untranslated region (UTR) bulged stem-loop showed no effect on (-)-strand sgmRNA synthesis; however, deletion of the 3' UTR pseudoknot decreased the yield of (-)-strand sgmRNA. (3) Nucleotides positioned from -15 to -34 of the sgmRNA 7 3'-terminal region are required for efficient (-)-strand sgmRNA synthesis. (4) Nucleotide species at the 3'-most position (-1) of sgmRNA 7 is correlated to the efficiency of (-)-strand sgmRNA synthesis. These results together suggest, in principle, that the 5'- and 3'-terminal sequences on sgmRNA 7 harbor cis-acting elements are critical for efficient (-)-strand sgmRNA synthesis in BCoV

Toward better intelligent learning (iLearning) performance:what makes iLearning work for students in a university setting?

We explored the critical factors associated with iLearning that impact students’ learning performance and identified the factors with a notable influence to help managers in higher education institutions increase the effectiveness of iLearning for students. We initially synthesised 4 main dimensions (including 26 criteria): performance expectancy, lecturers’ influence, quality of service, and personal innovativeness. Subsequently, we conducted surveys in two stages. First, by studying a group of students with experience using iLearning at Taiwanese universities, we extracted 5 critical dimensions (including 18 criteria) through a factor analysis. Second, by studying a group of senior educators and practitioners in Taiwan, we prioritised the dimensions and criteria through the analytic hierarchy process (AHP). We found that performance expectancy is the top critical dimension, and the top five critical criteria pertain to enhancing the learning performance, increasing the learning participation, altering learning habits, ensuring access at all times, and enabling prompt use of learning resources. Moreover, we recommend several suggestions for the relevant managers to enhance the students’ iLearning performance