Interactions of 3' terminal and 5' terminal regions of physalis mottle virus genomic RNA with its replication complex

Physalis mottle virus (PhMV) belongs to the tymogroup of positive-strand RNA viruses with a genome size of 6 kb. Crude membrane preparations from PhMV-infectedNicotiana glutinosa plants catalyzed the synthesis of PhMV genomic RNA from endogenously bound template. Addition of exogenous gnomic RNA enhanced the synthesis which was specifically inhibited by the addition of sense and antisense transcripts corresponding to 3' terminal 242 nucleotides as well as the 5' terminal 458 nucleotides of PhMV genomic RNA while yeast tRNA or ribosomal RNA failed to inhibit the synthesis. This specific inhibition suggested that the 5' and 3' non-coding regions of PhMV RNA might play an important role in viral replication

Seed Hardening and Moisture Conservation Practices to Mitigate Water Stress in Cowpea

Cowpea is an important protein catering feed/fodder for cattle. Being a non-season bound crop, it can be grown throughout the year and performs well during summer season under irrigation but water scarcity limits its area under cultivation. It necessitates the development of alternate management technologies to overcome the water stress period for the sustainable growth and yield of the crop. Seed hardening, soil moisture conservation measures like mulching and antitranspirant sprays are the techniques which helps the plant to survive under drought. So the present study was undertaken to evaluate the efficacy of various seed primers, antitranspirants and mulches for mitigating water stress in cowpea grown during summer season, to find out the best among each and also to assess the response of cowpea to these techniques under water stress conditions

Interaction of Sesbania Mosaic Virus Movement Protein with VPg and P10: Implication to Specificity of Genome Recognition

Sesbania mosaic virus (SeMV) is a single strand positive-sense RNA plant virus that belongs to the genus Sobemovirus. The mechanism of cell-to-cell movement in sobemoviruses has not been well studied. With a view to identify the viral encoded ancillary proteins of SeMV that may assist in cell-to-cell movement of the virus, all the proteins encoded by SeMV genome were cloned into yeast Matchmaker system 3 and interaction studies were performed. Two proteins namely, viral protein genome linked (VPg) and a 10-kDa protein (P10) c v gft encoded by OFR 2a, were identified as possible interacting partners in addition to the viral coat protein (CP). Further characterization of these interactions revealed that the movement protein (MP) recognizes cognate RNA through interaction with VPg, which is covalently linked to the 5′ end of the RNA. Analysis of the deletion mutants delineated the domains of MP involved in the interaction with VPg and P10. This study implicates for the first time that VPg might play an important role in specific recognition of viral genome by MP in SeMV and shed light on the possible role of P10 in the viral movement

Plant Growth Regulators for Mitigating Water Stress in Cowpea

Water is becoming a scarce commodity for irrigation especially under the present changing climatic scenario. Water stress hampers important physiological and biochemical mechanisms leading to reduction in plant growth and yield. Studies revealed that the exogenous application of plant hormones has been found to alleviate the negative effects of various abiotic stresses. Cowpea, being a non-season bound crop, can be grown throughout the year and it performs well during summer season under irrigation, but water scarcity limits its area under cultivation. However, limited research works have been conducted to investigate the potential benefits of exogenous application of plant growth regulators (PGRs) in cowpea grown under water stress conditions. So the present study was undertaken to evaluate the efficacy of exogenous application of certain plant growth regulators to mitigate water stress in cowpea, to find out an effective plant growth regulator for drought management and to assess the response of cowpea to these plant growth regulators

Similarities in the genomic sequence and coat protein structure of plant virsuses

The genomic sequences of several RNA plant viruses including cucumber mosaic virus, brome mosaic virus, alfalfa mosaic virus and tobacco mosaic virus have become available recently. The former two viruses are icosahedral while the latter two are bullet and rod shaped, respectively in particle morphology. The non-structural 3a proteins of cucumber mosaic virus and brome mosaic virus have an amino acid sequence homology of 35% and hence are evolutionarily related. In contrast, the coat proteins exhibit little homology, although the circular dichroism spectrum of these viruses are similar. The non-coding regions of the genome also exhibit variable but extensive homology. Comparison of the brome mosaic virus and alfalfa mosaic virus sequences reveals that they are probably related although with a much larger evolutionary distance. The polypeptide folds of the coat protein of three biologically distinct isometric plant viruses, tomato Bushy stunt virus, southern bean mosaic virus and satellite tobacco necrosis virus have been shown to display a striking resemblance. All of them consist of a topologically similar 8-standard β-Barrel. The implications of these studies to the understanding of the evolution of plant viruses will be discussed

Fruit and seed development in mung beans (Phaseolus aureus Roxb.)

A study of fruit set at different nodes was made in mung beans, Phaseolus aureus Roxb., under field conditions. Flowering commenced on the fourth node from the base and the percentage fruit set showed a gradual decrease from the fifth node upwards. Yield analysis was carried out for each of the fruiting nodes. When the leaf and inflorescences at a node are taken as a functional unit it is seen that there was a decrease in the ratio of leaf area to fruit and seed weights from the base of the plant upwards indicating that at the upper nodes particularly, some other plant parts also contribute to the photosynthate pool of the developing seeds. A quantitative study of the dry matter, proteins and starch in the fruit wall and seeds of fruits at different stages of development was made. It showed that the rapid increase in dry matter, proteins and starch in the seeds at the later stages of development is compensated, in part, by a decrease of these components in the fruit wall. Histochemical studies of the fruit wall further supported these observations. This indicated the contribution of substrates by the fruit wall to the developing seeds

Structure and assembly of Sesbania mosaic virus

Sesbania mosaic virus (SeMV) is a ss-RNA (4149 nt) plant sobemovirus isolated from farmer’s field around Tirupathi, Andhra Pradesh. The viral capsid (30 nm diameter) consists of 180 copies of protein subunits (MW 29 kDa) organized with icosahedral symmetry. In order to understand the mechanism of assembly of SeMV, a large number of deletion and substitution mutants of the coat protein (CP) were constructed. Recombinant SeMV CP (rCP) as well as the N-terminal rCP deletion mutant ΔN22 were found to assemble in E. coli into virus-like particles (VLPs). ΔN36 and ΔN65 mostly formed smaller particles consisting of 60 protein subunits. Although particle assembly was not affected due to the substitution of aspartates (D146 and D149) that coordinate calcium ions by asparagines, the stability of the resulting capsids was drastically reduced. Deletion of residues forming a characteristic β-annulus at the icosahedral 3-folds did not affect the assembly of VLPs. Mutation of a single tryptophan, which occurs near the icosahedral fivefold axis to glutamate or lysine, resulted in the disruption of the capsid leading to soluble dimers that resembled the quasi-dimer structure of the native virus. Replacement of positively charged residues in the amino terminal segment of CP resulted in the formation of empty shells. Based on these observations, a plausible mechanism of assembly is proposed

Evolutionary relationship of alfalfa mosaic virus with cucumber mosaic virus and brome mosaic virus

The amino acid sequences of the non-structural protein (molecular weight 35,000; 3a protein) from three plant viruses-cucumber mosaic, brome mosaic and alfalfa mosaic have been systematically compared using the partial genomic sequences for these three viruses already available. The 3a protein of cucumber mosaic virus has an amino acid sequence homology of 33.7% with the corresponding protein of brome mosaic virus. A similar protein from alfalfa mosaic virus has a homology of 18.2% and 14.2% with the protein from brome mosaic virus and cucumber mosaic virus, respectively. These results suggest that the three plant viruses are evolutionarily related, although, the evolutionary distance between alfalfa mosaic virus and cucumber mosaic virus or brome mosaic virus is much larger than the corresponding distance between the latter two viruses

Mathematical Modelling of Indian Regional Navigation Satellite System Receiver

At present the armoured fighting vehicles are equipped with either global positioning system (GPS) receivers or integrated inertial navigation system (INS)/GPS navigation systems. During hostile situations, the denial/degradation of the GPS satellite signals may happen. This results in the requirement of an indigenous satellite based navigation system. Indian Space Research Organisation has developed an indigenous Indian regional navigation satellite system (IRNSS), with a seven satellite constellation to provide independent position, navigation and timing services over India and its neighbouring regions. In this paper, the development of IRNSS receiver using MATLAB as per IRNSS signal in space interface control document for standard positioning service is discussed. A method for faster IRNSS signal acquisition in frequency domain and delay locked loop code tracking for the acquired satellite signals are used. Models for navigation message decoding and pseudo range/user position calculations are developed using the algorithms provided in IRNSS ICD

Arginine residues involved in binding of tetrahydrofolate to sheep liver serine hydroxymethyltransferase

The arginine residue(s) necessary for tetrahydrofolate binding to sheep liver serineh ydroxymethyltransferase were located by phenylglyoxal modification. The incorporation of [7-14C]phenylglyoxal indicated that 2 arginine residues were modified per subunit of the enzyme and the modification of these residues was prevented by tetrahydrofolate. In order to locate the sites of phenylglyoxal modification, the enzyme was reacted in the presence and absence of tetrahydrofolate using unlabeled and radioactive phenylglyoxal, respectively. The labeled phenylglyoxal-treated enzyme was digested with trypsin, and the radiolabeled peptides were purified by high-performance liquid chromatography on reversed-phase columns. Sequencing the tryptic peptides indicated that Arg-269 and Arg-462 were the sites of phenylglyoxal modification. Neither a spectrally discernible 495-nm intermediate (characteristic of the native enzyme when substrates are added) nor its enhancement by the addition of tetrahydrofolate, was observed with the phenylglyoxalmodified enzyme. There was no enhancement of the rate of the exchange of the α-proton of glycine upon addition of tetrahydrofolate to the modified enzyme as was observed with the native enzyme. These results demonstrate the requirement of specific arginine residues for the interaction of tetrahydrofolate with sheep liver serine hydroxymethyltransferase