Comparison of methylprednisolone with dexamethasone in treatment of acute spinal injury in rats

Effect of methylprednisolone sodium succinate (MPSS) and its comparison with dexamethasone in experimentally induced acute spinal cord compression in adult rats was studied. The rats were divided into group A (control) and group B, which was subdivided into B1, B2, B3 where MPSS was given after 1, 8 and 24 hr and B4 where dexamethasone was given after 1 hr of cord injury respectively. Proper neurological evaluation was done with mobility, running and climbing score. Recovery index was evaluated for 7 days. After sacrificing the rats, spinal cord was observed histopathologically. Mean recovery index and microscopic findings based on hemorrhage in gray and white matter, neuronal degeneration, hematomyelia and edema in white matter were recorded. The results suggested that MPSS was effective in promoting post-traumatic clinical and histological recovery and to a greater extent, when given 1 hr after trauma. MPSS is more effective than dexamethasone in reducing edema when both are given after interval of 1 hr.     

Fluorescence correlation spectroscopy studies of Peptide and protein binding to phospholipid vesicles

We used fluorescence correlation spectroscopy (FCS) to analyze the binding of fluorescently labeled peptides to lipid vesicles and compared the deduced binding constants to those obtained using other techniques. We used a well-characterized peptide corresponding to the basic effector domain of myristoylated alanine-rich C kinase substrate, MARCKS(151-175), that was fluorescently labeled with Alexa488, and measured its binding to large unilamellar vesicles (diameter approximately 100 nm) composed of phosphatidylcholine and phosphatidylserine or phosphatidylinositol 4,5-bisphosphate. Because the large unilamellar vesicles are significantly larger than the peptide, the correlation times for the free and bound peptide could be distinguished using single color autocorrelation measurements. The molar partition coefficients calculated from the FCS measurements were comparable to those obtained from binding measurements of radioactively labeled MARCKS(151-175) using a centrifugation technique. Moreover, FCS can measure binding of peptides present at very low concentrations (1-10 nmolar), which is difficult or impossible with most other techniques. Our data indicate FCS can be an accurate and valuable tool for studying the interaction of peptides and proteins with lipid membranes.     

Intragenic codon bias in a set of mouse and human genes

To better conceptualize the mechanism underlying the evolution of synonymous codons, we have analysed intragenic codon usage in chosen "regions" of some mouse and human genes. We divided a given gene into two regions: one consisting of a trinucleotide repeat (TNR) and the other consisting of the "rest of the coding region" (RCR). Usually, a TNR is composed of a repetitive single codon, which may reflect its frequency in a gene. In contrast, a non-random frequency of a codon in the RCR versus TNR (or vice versa) of a gene should indicate a bias for that codon within the TNR. We examined this scenario by comparing codon frequency between the RCR and the cognate TNR(s) for a set of human and mouse genes. A TNR length of six amino acids or more was used to identify genes from the Genbank database. Twenty nine human and twenty one mouse genes containing TNRs coding for nine different amino acid runs were identified. The ratio of codon frequency in a TNR versus the corresponding RCR was expressed as "fold change" which was also regarded as a measure of codon bias (defined as preferential use either in TNR or in RCR). Chi-square values were then determined from the distribution of codon frequency in a TNR vs. the cognate RCR. At p<0.001, 22% and 27%, respectively, of human and mouse TNRs showed codon bias. Greater than 40% of the TNRs (29 out of 69 in human, and 18 of 42 in mouse) showed codon bias at p<0.05. In addition, we identify eight single-codon TNRs in mouse and ten in human genes. Thus, our results show intragenic codon bias in both mouse and human genes expressed in diverse tissue types. Since our results are independent of the Codon Adaptation Index (CAI) and starvation CAI, and since the tRNA repertoire in a cell or in a tissue is constant, our data suggest that other constraints besides tRNA abundance played a role in creating intragenic codon bias in these genes.     

Hypoxia induced non-apoptotic cellular changes during aerenchyma formation in rice (Oryza sativa L.) roots

The stress of low oxygen concentrations in a waterlogged environment is minimized in some plants that produce aerenchyma, a tissue characterized by prominent intercellular spaces. It is produced by the predictable collapse of root cortex cells, indicating a programmed cell death (PCD) and facilitates gas diffusion between root and the aerial environment. The objective of this study was to characterize the cellular changes take place during aerenchyma formation in root of rice that accompany PCD. Scanning electron microscopy and transmission electron microscopy were used for cellular analysis of roots. Aerenchyma development was observed in both aerobic and flooded conditions. Structural changes in membranes and organelles were examined during development of root cortex cells to compare with previous examples of PCD. There was an initial collapse which started at a specific position in the mid cortex, indicating loss of turgor, and the cytoplasm became more electron dense. These cells were distinct in shape from those located towards the periphery. Mitochondria and endoplasmic reticulum appeared normal at this early stage though the tonoplast lost its integrity. Subsequently it underwent further degeneration while the plasmalemma retracted from the cell wall followed by death of neighboring cells followed a radial path. However, pycnosis of the nucleus, blebbing of plasma membrane and production of apoptotic bodies were not found which in turn indicated nonapoptotic PCD during aerenchyma formation in rice.     

Plant Growth–Promoting Pseudomonas sp. Strains Reduce Natural Occurrence of Anthracnose in Soybean (Glycine max L.) in Central Himalayan Region

Biological control is an accepted important component of current plant disease management strategies. Introduction of bacterized seeds carrying bacterial isolates with proven growth-promotion capabilities and antagonistic characteristics offer a valid alternative to chemical protectants. Root colonization of disease-susceptible (PS 1024) and moderately resistant (PS1042) varieties of soyabean (Glycine Max L) by fluorescent pseudomonad (FLPs) strains GRP₃, PEn-4, PRS₁, and WRS-24 was studied in relation to natural occurrence of anthracnose caused by Colletotrichum dematium (Pers Ex Fr.) Grove. Rhizoplane population of FLPs was maintained at a critical level (5.3 cfu) up to 30 days of plant growth, followed by a steep decline. Indigenous FLPs population, however, remained nearly unchanged (3.0 to 2.4 log g⁻¹ root) between 30 days and 75 days of plant growth. The relative FLPs population in rhizosphere was lower than that in rhizoplane. Although intervarietal difference was observed, the root/shoot length remained unaffected. Compared to nonbacterized control, dry root weight was improved by FLPs treatment. Severity of foliar anthracnose was reduced significantly after FLPs treatment in the variety PS 1042. Because the point of FLPs treatment (seed bacterization) was away from the site of disease appearance (leaf), operation of induced systemic resistance in strains PEn-4 and GRP₃ appears imminent.     

Characterization of Mycolytic Enzymes of Bacillus Strains and Their Bio-Protection Role Against Rhizoctonia solani in Tomato

Four antagonists bacteria namely, Bacillus megaterium MB3, B. subtilis MB14, B. subtilis MB99 and B. amyloliquefaciens MB101 were able to produce chitinase, β-1,3-glucanase and protease in different range with the presence of Rhizoctonia solani cell wall as a carbon source. Amplification of chitinase (chiA) gene of 270 bp and β-1, 3-glucanase gene of 415 bp was given supportive evidence at molecular level of antibiosis. After in vitro screening, all antagonists were tested against R. solani under greenhouse conditions. Root treatment of Bacillus strains showed superior defense during pathogen suppression in terms of chitinase, glucanase, peroxidase, poly phenol oxidase, phenylalanine ammonia-lyase activity and total phenolic content in leaves of tomato. All these enzymes accumulated high in tomato leaves as compared to roots. Pathogenesis-related proteins and defense-related enzymes accumulation was directly correlated with plant protection and greenhouse results indicated that B. amyloliquefaciens MB101- and B. subtilis MB14-treated plants offered 69.76 and 61.51 % disease reductions, respectively, over the infected control. These results established that these organisms have the potential to act as biocontrol agents. This study could be highlighted a mutual importance of liquid formulation of antagonistic Bacillus spp. against root associated sclerotia former pathogen R. solani.     

A structural model for the generation of continuous curvature on the surface of a retroviral capsid

The genome of a retrovirus is surrounded by a convex protein shell, or capsid, that helps facilitate infection. The major part of the capsid surface is formed by interlocking capsid protein (CA) hexamers. We report electron and X-ray crystallographic analysis of a variety of specimens assembled in vitro from Rous sarcoma virus (RSV) CA. These specimens all contain CA hexamers arranged in planar layers, modeling the authentic capsid surface. The specimens differ only in the number of layers incorporated and in the disposition of each layer with respect to its neighbor. The body of each hexamer, formed by the N-terminal domain of CA, is connected to neighboring hexamers through C-terminal domain dimerization. The resulting layer structure is very malleable due to inter-domain flexibility. A helix-capping hydrogen bond between the two domains of RSV CA creates a pivot point, which is central to controlling their relative movement. A similar mechanism for the governance of inter-domain motion was recently described for the human immunodeficiency virus type 1 (HIV-1) capsid, although there is negligible sequence identity between RSV and HIV-1 CA in the region of contact, and the amino acids involved in creating the pivot are not conserved. Our observations allow development of a physically realistic model for the way neighboring hexamers can tilt out of plane, deforming the hexamer layer and generating the continuously curved surfaces that are a feature of all retroviral capsids.