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Wireless communication technologies like GPRS, UMTS and WLAN, combined with the availability of high-end, affordable mobile devices enable the development of the advanced and innovative mobile services. Devices such as mobile phones and Personal Digital Assistants let the users access a wide range of new offerings whenever and wherever they happen to be. A strategic approach for the quality assurance of these mobile data services should take into account a number of characteristics unique to the mobile paradigm, the increased complexity of emerging handheld devices, the greater sensitivity to security and load related problems in wireless infrastructure and increased complexities of scale. This paper identifies the major factors influencing the development and testing strategies for these applications and accordingly elaborates effective quality assurance principles to ensure productive and scalable mobile data services

Role of human GRP75 in miRNA mediated regulation of dengue virus replication

In recent times, RNAi has emerged as an important defence system that regulates replication of pathogens in host cells. Many RNAi related host factors especially the host miRNAs play important roles in all intrinsic cellular functions, including viral infection. We have been working on identification of mammalian host factors involved in Dengue virus infection. In the present study, we identified Glucose Regulated Protein 75kDa (GRP75), as a host factor that is associated with dicer complex, in particular with HADHA (trifunctional enzyme subunit alpha, mitochondrial), an auxiliary component of dicer complex. Knockdown of GRP75 by respective siRNAs in Huh-7 cells resulted in the accumulation of dengue viral genomic RNA suggesting a role of GRP75 in regulating dengue virus replication in human cell lines. To elucidate the mode of action of GRP75, we over expressed the protein in Huh-7 cells and analysed the host miRNAs processing. The results revealed that, GRP75 is involved in processing of host miRNA, hsa-mir-126, that down regulates dengue virus replication. These findings suggest a regulatory role of human miRNA pathway especially GRP75 protein and hsa-mir-126 in dengue virus replication. These results thus provide insights into the role of miRNAs and RNAi machinery in dengue life cycle

Discrete wavelet transform de-noising in eukaryotic gene splicing

<p>Abstract</p> <p>Background</p> <p>This paper compares the most common digital signal processing methods of exon prediction in eukaryotes, and also proposes a technique for noise suppression in exon prediction. The specimen used here which has relevance in medical research, has been taken from the public genomic database - GenBank.</p> <p>Methods</p> <p>Here exon prediction has been done using the digital signal processing methods viz. binary method, EIIP (electron-ion interaction psuedopotential) method and filter methods. Under filter method two filter designs, and two approaches using these two designs have been tried. The discrete wavelet transform has been used for de-noising of the exon plots.</p> <p>Results</p> <p>Results of exon prediction based on the methods mentioned above, which give values closest to the ones found in the NCBI database are given here. The exon plot de-noised using discrete wavelet transform is also given.</p> <p>Conclusion</p> <p>Alterations to the proven methods as done by the authors, improves performance of exon prediction algorithms. Also it has been proven that the discrete wavelet transform is an effective tool for de-noising which can be used with exon prediction algorithms.</p

Role of RNA interference (RNAi) in dengue virus replication and identification of NS4B as an RNAi suppressor

RNA interference (RNAi) is an important antiviral defense response in plants and invertebrates; however, evidences for its contribution to mammalian antiviral defense are few. In the present study, we demonstrate the anti-dengue virus role of RNAi in mammalian cells. Dengue virus infection of Huh 7 cells decreased the mRNA levels of host RNAi factors, namely, Dicer, Drosha, Ago1, and Ago2, and in corollary, silencing of these genes in virus-infected cells enhanced dengue virus replication. In addition, we observed downregulation of many known human microRNAs (miRNAs) in response to viral infection. Using reversion-of-silencing assays, we further showed that NS4B of all four dengue virus serotypes is a potent RNAi suppressor. We generated a series of deletion mutants and demonstrated that NS4B mediates RNAi suppression via its middle and C-terminal domains, namely, transmembrane domain 3 (TMD3) and TMD5. Importantly, the NS4B N-terminal region, including the signal sequence 2K, which has been implicated in interferon (IFN)-antagonistic properties, was not involved in mediating RNAi suppressor activity. Site-directed mutagenesis of conserved residues revealed that a Phe-to-Ala (F112A) mutation in the TMD3 region resulted in a significant reduction of the RNAi suppression activity. The green fluorescent protein (GFP)-small interfering RNA (siRNA) biogenesis of the GFP-silenced line was considerably reduced by wild-type NS4B, while the F112A mutant abrogated this reduction. These results were further confirmed by in vitro dicer assays. Together, our results suggest the involvement of miRNA/RNAi pathways in dengue virus establishment and that dengue virus NS4B protein plays an important role in the modulation of the host RNAi/miRNA pathway to favor dengue virus replication

Mammalian microRNA: an important modulator of host-pathogen interactions in human viral infections

MicroRNAs (miRNAs), which are small non-coding RNAs expressed by almost all metazoans, have key roles in the regulation of cell differentiation, organism development and gene expression. Thousands of miRNAs regulating approximately 60æ% of the total human genome have been identified. They regulate genetic expression either by direct cleavage or by translational repression of the target mRNAs recognized through partial complementary base pairing. The active and functional unit of miRNA is its complex with Argonaute proteins known as the microRNA-induced silencing complex (miRISC). De-regulated miRNA expression in the human cell may contribute to a diverse group of disorders including cancer, cardiovascular dysfunctions, liver damage, immunological dysfunction, metabolic syndromes and pathogenic infections. Current day studies have revealed that miRNAs are indeed a pivotal component of host-pathogen interactions and host immune responses toward microorganisms. miRNA is emerging as a tool for genetic study, therapeutic development and diagnosis for human pathogenic infections caused by viruses, bacteria, parasites and fungi. Many pathogens can exploit the host miRNA system for their own benefit such as surviving inside the host cell, replication, pathogenesis and bypassing some host immune barriers, while some express pathogen-encoded miRNA inside the host contributing to their replication, survival and/or latency. In this review, we discuss the role and significance of miRNA in relation to some pathogenic viruses

Dengue NS3, an RNAi suppressor, modulates the human miRNA pathways through its interacting partner

RNAi acts as a host immune response against non-self molecules, including viruses. Viruses evolved to neutralize this response by expressing suppressor proteins. In the present study, we investigated dengue virus non structural protein 3 (dvNS3), for its RNAi-suppressor activity in human cell lines. Dengue virus (DV) NS3 reverts the GFP expression in GFP-silenced cell lines. Pull-down assays of dvNS3 revealed that it interacts with the host factor human heat shock cognate 70 (hHSC70). Down-regulation of hHSC70 resulted in accumulation of dengue viral genomic RNA. Also, the interaction of dvNS3 with hHSC70 perturbs the formation of RISC (RNA-induced silencing complex)-loading complex (RLC), by displacing TRBP (TAR RNA-binding protein) and possibly impairing the downstream activity of miRNAs. Interestingly, some of these miRNAs have earlier been reported to be down-regulated upon DV infection in Huh7 cells. Further studies on the miRNA-mRNA relationship along with mRNA profiling of samples overexpressing dvNS3 revealed up-regulation of TAZ (tafazzin) and SYNGR1 (synaptogyrin 1), known dengue viral host factors (DVHFs). Importantly, overexpression of dvNS3 in human embryonic kidney (HEK) 293T cells resulted in modulation of both mature and precursor miRNAs in human cell lines. Subsequent analysis suggested that dvNS3 induced stage-specific down-regulation of miRNAs. Taken together, these results suggest that dvNS3 affects biogenesis and function of host miRNAs to regulate DVHFs for favouring DV replication