Defence Research Laboratory DRDO

Sonitpur, India

Defence Research Laboratory DRDO

Sonitpur, India
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Datta S.,Defence Research Laboratory DRDO | Budhauliya R.,Defence Research Laboratory DRDO | Chatterjee S.,Defence Research Laboratory DRDO | Vanlalhmuaka,Defence Research Laboratory DRDO | And 2 more authors.
Molecular Diagnosis and Therapy | Year: 2016

Background: Polymerase chain reaction (PCR) is widely used in biological research and diagnostics because of its high sensitivity and specificity. However, the sensitivity of PCR is strongly influenced by topological characteristics of the template. Supercoiled templates are known to inhibit PCR, whereas linearized forms of the same supercoiled templates facilitate PCR. Objectives: This study was conducted to compare the PCR efficiency of circular supercoiled DNA templates to their restriction endonuclease (RE)-mediated linearized forms. Additionally, we also evaluated the possibility of RE digestion of the circular supercoiled templates within the complete PCR buffer. Methods: Following a systematic approach, we demonstrated that circular supercoiled templates could be efficiently linearized by RE in the complete PCR buffer itself. This allowed linearization of circular supercoiled templates and their subsequent amplification in the PCR buffer in a single-tube format. Results: Using this extremely simple RE-PCR approach, we documented up to tenfold increases in detection efficiency of PCR with two different circular supercoiled templates of clinical origin, including an international calibration standard. Conclusions: This inexpensive and easy approach to increasing PCR sensitivity can be easily adapted to any standard PCR protocol aimed at amplifying circular supercoiled genomes. Apart from its application in the development of sensitive clinical diagnostic PCR assays for a large number of organisms, this method could also prove to be very useful in simplifying the existing protocols for other applications where pre-PCR restriction digestion is required, such as mutation detection, genotyping, and selective template amplification. © 2016 Springer International Publishing Switzerland


PubMed | Hepatitis Research Laboratory and Defence Research Laboratory DRDO
Type: Journal Article | Journal: Molecular diagnosis & therapy | Year: 2016

Polymerase chain reaction (PCR) is widely used in biological research and diagnostics because of its high sensitivity and specificity. However, the sensitivity of PCR is strongly influenced by topological characteristics of the template. Supercoiled templates are known to inhibit PCR, whereas linearized forms of the same supercoiled templates facilitate PCR.This study was conducted to compare the PCR efficiency of circular supercoiled DNA templates to their restriction endonuclease (RE)-mediated linearized forms. Additionally, we also evaluated the possibility of RE digestion of the circular supercoiled templates within the complete PCR buffer.Following a systematic approach, we demonstrated that circular supercoiled templates could be efficiently linearized by RE in the complete PCR buffer itself. This allowed linearization of circular supercoiled templates and their subsequent amplification in the PCR buffer in a single-tube format.Using this extremely simple RE-PCR approach, we documented up to tenfold increases in detection efficiency of PCR with two different circular supercoiled templates of clinical origin, including an international calibration standard.This inexpensive and easy approach to increasing PCR sensitivity can be easily adapted to any standard PCR protocol aimed at amplifying circular supercoiled genomes. Apart from its application in the development of sensitive clinical diagnostic PCR assays for a large number of organisms, this method could also prove to be very useful in simplifying the existing protocols for other applications where pre-PCR restriction digestion is required, such as mutation detection, genotyping, and selective template amplification.


Nath M.J.,Defence Research Laboratory DRDO | Bora A.,Gauhati University | Talukdar P.K.,Defence Research Laboratory DRDO | Das N.G.,Defence Research Laboratory DRDO | And 3 more authors.
Geocarto International | Year: 2012

Assam-Arunachal forest fringed foothill area is endemic for malaria incidence. The present study deals with the temporal analysis of malaria incidence and determines its association with deforestation in 24 villages along the Assam-Arunachal forest fringed foothill area of Sonitpur district of Assam. Malaria epidemiological survey has been carried out in the study area from the year 1994 to 2005. Remote sensing (RS) technique has been used to map the areas of forest changes from the year 2000 to 2005. Geographical information system (GIS) was used to map the malaria incidence and forest cover. The study villages are endemic to malaria infections and there was increasing trend of malaria incidence over the years. The slide positivity rate (SPR) ranged from 5.1% in 1997 to 44.4% in 2005. The percentage forest cover decreased significantly from 23.6% during 2000 to 15.4% during 2005, whereas SPR was increased during 2000-2005. The present study is the first attempt to understand the role of deforestation in malaria incidence using RS and GIS in the north-eastern region of India at a micro-geographic level. The study suggests that the area is endemic to malaria transmission. The decrease in forest cover is a serious ecological concern besides its role in elevating the malaria incidence in the study area. © 2012 Copyright Taylor and Francis Group, LLC.


Sarkar M.,Defence Research Laboratory DRDO | Baruah I.,Defence Research Laboratory DRDO | Srivastava R.B.,Directorate of Life Science | Borkotoki A.,Gauhati University | Bhattacharyya I.K.,Cotton College
Pest Management Science | Year: 2011

BACKGROUND: Knockdown resistance (kdr) mutation (L1014F) is a well-defined mechanism of resistance to pyrethroids and DDT in many insect species. Sensitive detection of the mutations associated with resistance is a prerequisite for resistance management strategies. The authors have developed a new real-time molecular diagnostic assay based on SimpleProbe ®/melting curve analysis for large-scale kdr genotyping in the wild population of Culex quinquefasciatus Say, the principal vector of bancroftian filariasis. Melting curve analysis is based on the thermal stability difference between matched and mismatched DNA duplexes. The application of SimpleProbe ® chemistry in insects described here is novel in entomology research.RESULTS: The mosquitoes homozygous for knockdown-resistant and knockdown-susceptible allele showed melting peaks at 60.45 °C (± 0.25) and 64.09 °C (± 0.24) respectively. The heterozygous mosquitoes yielded both peaks at approximately 60.5 °C (± 0.2) and 64.20 °C (± 0.23). Among the 92 samples genotyped, 16 were found to be homozygous resistant, 44 homozygous susceptible and 32 heterozygous. Comparative assessments were made of all the reported methods for kdr genotyping.CONCLUSION: The present method is cheaper, faster, more reliable and versatile than other alternatives proposed in detecting correct kdr genotypes in mosquitoes. This is the first report using a single-labelled hybridisation probe to detect point mutations in insect populations. © 2010 Society of Chemical Industry Copyright © 2010 Society of Chemical Industry.


Datta S.,Defence Research Laboratory DRDO | Gopalakrishnan R.,Defence Research Laboratory DRDO | Chatterjee S.,Defence Research Laboratory DRDO | Veer V.,Defence Research Laboratory DRDO
Intervirology | Year: 2015

Objective: We report the phylogenetic characterization of a unique flavivirus sequence detected in a wild Culex tritaeniorhynchus mosquito pool, collected from the northeast Indian state of Assam. Methods: DNA and RNA were extracted from field-collected mosquito pools. Extracts were subjected to PCR and reverse transcriptase PCR amplification using universal and type-specific primers for direct detection of flavivirus-specific viral nucleic acids. An amplified flavivirus nonstructural protein 5 (NS5) genetic region was sequenced and BLAST searched, and phylogenetic analyses performed with reference sequences retrieved from GenBank. Results: Phylogenetic analyses revealed the sequence to be related to insect-specific flaviviruses (ISFs) of the genus Flavivirus, family Flaviviridae. Despite being related to the Palm Creek virus (PCV; an ISF very recently reported from Northern Australia), the present sequence (provisionally named Assam virus) was found to be highly divergent from PCV and other ISF sequences available in GenBank. The partial NS5 sequence analysis demonstrated low nucleotide sequence identity (66-77%) with known ISFs reported from other parts of the globe. Conclusion: Findings of this study suggest the presence of a candidate novel ISF - the first to be reported from India. © 2015 S. Karger AG, Basel.


Singha I.M.,Defence Research Laboratory DRDO | Kakoty Y.,CSIR - Central Electrochemical Research Institute | Unni B.G.,CSIR - Central Electrochemical Research Institute | Kalita M.C.,Gauhati University | And 4 more authors.
World Journal of Microbiology and Biotechnology | Year: 2011

The main objective of this study was to evaluate the effectiveness of crude chloroform extract of Piper betle L. (PbC) in controlling Fusarium wilt of tomato (Lycopersicon esculentum) caused by Fusarium oxysporum f. sp. lycopersici. It was observed that 1% (w/w) amendment of the PbC in soil was more efficient in reducing the Fusarium population in soil than carbendazim and the combined amendment of carbendazim and PbC. Fusarium wilt control studies were carried out in a greenhouse. Variation in different parameters like shoot growth, root growth and mean fresh weights of tomato seedlings in all the treatments were recorded. Accumulation of total phenolics was also studied from the root tissues of tomato. Higher accumulation of total phenolics was observed in the Fusarium-infested plants as compared to that of healthy control and PbC-treated plants. Moreover, it was observed that the extract could reduce the symptoms and disease development. Electron microscopy studies were also done to observe the Fusarium infestation in the vascular bundles and to show the accumulation of total phenolics in the vacuoles of root tissue. © 2011 Springer Science+Business Media B.V.


Phatik T.,Darrang College | Das J.,Defence Research Laboratory Drdo | Boruah P.,Northeast Institute Of Science And Technology Csir
Plant Archives | Year: 2014

Antifungal activity of leaf extracts of Polygonum hydropiper and Solanum melongena were tested against Colletotrichum capsici, Curvularia lunata, Rhizoctonia solani and Sclerotinia sclerotiorum, causing severe losses in many economically important crop plants. The ethanolic leaf extracts were found to be effective against the pathogens, when compared with commercial fungicide in-vitro. The maximum zone of inhibition formed by the test extract at 2% concentration were 36.33 mm, 37.33 mm and 30.66 mm in C. lunata, S. sclerotiorum and R. Solani, respectively in P. hydropiper whereas 34.33 mm, 36.24 mm and 32.33 mm in C. capsici, S. sclerotiorum and R. solani respectively in case of S. melongena extracts. It was observed that the inhibitory effect of the commercial fungicide (Dithane M-45) was marginally higher.


PubMed | Defence Research Laboratory DRDO
Type: Journal Article | Journal: World journal of hepatology | Year: 2015

Hepatitis B virus (HBV) is classically considered to be hepatotropic, but accumulating evidences strongly support its extra-hepatotropic nature too. HBV nucleic acids and proteins have long been reported in a variety of extra-hepatic tissues. Of these, HBV has been studied in details in the peripheral blood mononuclear cells (PBMCs), due to its accessibility. From these studies, it is now well established that PBMCs are permissive to HBV infection, replication, transcription and production of infective virions. Furthermore, molecular evolutionary studies have provided definite evidences towards evolution of HBV genome in PBMCs, which is independent of evolution occurring in the liver, leading to the emergence and selection of compartment specific escape variants or drug resistant strains. These variants/resistant strains of HBV remain restricted within the PBMCs and are rarely detected in the serum/plasma. In addition, HBV infected PBMCs have been reported to be directly transmitted through intrauterine modes, and this infection does not correlate significantly with serum HBV surface antigen or HBV DNA markers. This editorial briefly reviews the current knowledge on this topic, emphasizes and delineates the gaps that are required to be filled to properly understand the biological and clinical relevance of extrahepatic tropism of HBV.


PubMed | Defence Research Laboratory DRDO
Type: Journal Article | Journal: Intervirology | Year: 2015

We report the phylogenetic characterization of a unique flavivirus sequence detected in a wild Culex tritaeniorhynchus mosquito pool, collected from the northeast Indian state of Assam.DNA and RNA were extracted from field-collected mosquito pools. Extracts were subjected to PCR and reverse transcriptase PCR amplification using universal and type-specific primers for direct detection of flavivirus-specific viral nucleic acids. An amplified flavivirus nonstructural protein 5 (NS5) genetic region was sequenced and BLAST searched, and phylogenetic analyses performed with reference sequences retrieved from GenBank.Phylogenetic analyses revealed the sequence to be related to insect-specific flaviviruses (ISFs) of the genus Flavivirus, family Flaviviridae. Despite being related to the Palm Creek virus (PCV; an ISF very recently reported from Northern Australia), the present sequence (provisionally named Assam virus) was found to be highly divergent from PCV and other ISF sequences available in GenBank. The partial NS5 sequence analysis demonstrated low nucleotide sequence identity (66-77%) with known ISFs reported from other parts of the globe.Findings of this study suggest the presence of a candidate novel ISF - the first to be reported from India.


PubMed | Defence Research Laboratory DRDO
Type: Journal Article | Journal: Journal of environmental health science & engineering | Year: 2014

The adsorption potential of iron acetate coated activated alumina (IACAA) for removal of arsenic [As (III)] as arsenite by batch sorption technique is described. IACAA was characterized by XRD, FTIR, EDAX and SEM instruments. Percentage adsorption on IACAA was determined as a function of pH, contact time and adsorbent dose. The study revealed that the removal of As (III) was best achieved at pH =7.4. The initial As (III) concentration (0.45mg/L) came down to less than 0.01mg/L at contact time 90min with adsorbent dose of 1g/100mL. The sorption was reasonably explained with Langmuir and Freundlich isotherms. The thermodynamic parameters such as G0, H0, S0 and Ea were calculated in order to understand the nature of sorption process. The sorption process was found to be controlled by pseudo-second order and intraparticle diffusion models.

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