Molecular biology and pathogenesis of hepatitis E virus

The hepatitis E virus (HEV) is a small RNA virus and the etiological agent for hepatitis E, a form of acute viral hepatitis. The virus has a feco-oral transmission cycle and is transmitted through environmental contamination, mainly through drinking water. Recent studies on the isolation of HEV-like viruses from animal species also suggest zoonotic transfer of the virus. The absence of small animal models of infection and efficient cell culture systems has precluded virological studies on the replication cycle and pathogenesis of HEV. A vaccine against HEV has undergone successful clinical testing and diagnostic tests are available. This review describes HEV epidemiology, clinical presentation, pathogenesis, molecular virology and the host response to HEV infection. The focus is on published literature in the past decade. Equal contribution     

Efficient phosphorus solubilization by mutant strain of Xanthomonas campestris using different carbon, nitrogen and phosphorus sources

The phosphate solubilization activity of Xanthomonas campestris was measured in both the wild type and mutant strains using various carbon and nitrogen sources. Glucose was found to be the best in both (wild 39.9%; mutant 67.1%) strains followed by sucrose (46.8%) in the mutant and molasses (36.0%) in the wild type. Ammonium sulphate was the best nitrogen source for both the strains, followed by ammonium nitrate and urea. Dicalcium phosphate (DCP) was solubilized maximally by both the strains followed by tricalcium phosphate (TCP) and rock phosphate (RP) when various concentrations of different phosphate sources were tested.     

Incidence of Prunus necrotic ring spot virus on Malus domestica in India

In surveys of apple (Malus domestica) orchards in various parts of Himachal Pradesh, samples from trees showing necrotic symptoms on the leaves were collected and tested for detection of Prunus necrotic ringspot virus (PNRSV) initially by ELISA followed by RT‐PCR using coat protein gene primers. Positive results were obtained in samples from Kullu and Kalpa regions. The virus gene sequences showed 88–97% similarity to corresponding sequences of other PNRSV isolates deposited in the GenBank database using ncbi.nih.nlm.gov. Although the similarity was high, there were some distinct differences with the Spanish isolate. This is the first report of PNRSV in apple from India.     

Multiplicity of Quorum Quenching Enzymes: A Potential Mechanism to Limit Quorum Sensing Bacterial Population

Bacteria express certain of their characteristics especially, pathogenicity factors at high cell densities. The process is termed as quorum sensing (QS). QS operates via signal molecules such as acylhomoserine lactones (AHLs). Other bacteria inhibit QS through the inactivation of AHL signals by producing enzymes like AHL-lactonases and -acylases. Comparative genomic analysis has revealed the multiplicity of genes for AHL lactonases (up to 12 copies per genome) among Bacillus spp. and that of AHL-acylases (up to 5 copies per genome) among Pseudomonas spp. This genetic evolution can be envisaged to enable host to withstand the attacks from bacterial population, which regulates its functioning through QS.     

Upland interfluve (Doab) deposition: Alternative model to muddy overbank deposits

Summary Major alluvial plains contain large tracts of fine-grained muddy sediments, deposited away from the main river channels, which are mostly classed as overbank or floodplain deposits. Systematic study of the Ganga plain shows that such large tracts of deposition of muddy sediments are located several metres above the major channels, and are not flooded by overtopping of the major river channels. These surfaces are here designated as upland interfluve areas (Doab) where deposition of fine-grained sediments takes place independent of the processes operating in the main channels. The surfaces show distinct depositional domains with characteristic deposits. These include higher sloping surfaces (mottled silt), lower flat surfaces (variegated clayey silt), gulleys (sandy silt), small channels (mottled silty sand), ponds (shelly sandy clayey silt), lakes (shelly clayey silt). These deposits are prone to diagenetic changes, especially the development of calcrete horizons. Redistribution of these domains through time produces characteristic mud-dominant alluvial stratigraphy as observed in the Late Quaternary deposits of the Ganga plain. This succession shows similarity to mud-dominant deposits of the Siwalik succession. These Doab deposits are distinct from the overbank deposits formed close to the river channels affected by channel processes. It is argued that many of the thick mud-dominant fluvial deposits of the ancient fluvial record are products of deposition in upland interfluve areas.     

A magnetic nanoparticles-zinc oxide/zinc hexacyanoferrate hybrid film for amperometric determination of tyrosine

A method is described for the construction of a highly sensitive amperometric sensor for the detection of tyrosine, employing a magnetic nanoparticles-zinc oxide/zinc hexacyanoferrate (Fe₃O₄NP-ZnO/ZnHCF) hybrid film electrodeposited on the surface of a Pt electrode as working electrode. The sensor is based on electrocatalytic mechanism initiated by electrochemical oxidation of the reduced form of the hybrid film at +0.2 V vs. Ag/AgCl followed by completion of chemical oxidation of tyrosine. The sensor showed optimum response within 2 s at pH 2. The working/linear range of the sensor was 0.02–2.76 mM with a detection limit of 4 μM. The sensor measured tyrosine level in serum, a potential biomarker of phenylketonuria. The working electrode lost only 5 % of its initial activity, when stored at 4 °C, after its regular use over a period of 100 days.     

Plant regeneration from various expiants of cultivated Piper species

Morphogenetic potential of root, leaf, node and internode expiants of 3 cultivated Piper species was investigated to develop a reliable plant regeneration protocol. P. longum (pipli) was the most responsive followed by P. betle (betel vine) and P. nigrum (black pepper). In P. longum the highest number of shoot buds was produced on root expiants followed by node, internode and leaf expiants. In P. betle and P. nigrum adventitious shoot buds differentiated only from internodal and nodal ring regions, respectively. Histological examination in P. longum showed that adventitious shoot buds originate directly from the cortical cells of the root and the internode without an intervening callus phase. Benzyladenine was superior to kinetin for shoot induction and its optimum concentrations for P. longum, P. betle and P. nigrum were 1–2, 10 and 10 M, respectively. Shoot elongation and rooting were achieved in B₅ medium containing 0.5 M benzyladenine and 1 M indoleacetic acid, respectively. Regenerated plants were established in soil.Abbreviations BA N⁶ benzyladenine - B₅ medium Gamborg et al. (1968) medium - IAA indole-3-acetic acid